openssl/providers/implementations/signature/rsa_sig.c

/*
 * Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

/*
 * RSA low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#include <string.h>
#include <openssl/crypto.h>
#include <openssl/core_dispatch.h>
#include <openssl/core_names.h>
#include <openssl/err.h>
#include <openssl/rsa.h>
#include <openssl/params.h>
#include <openssl/evp.h>
#include <openssl/proverr.h>
#include "internal/cryptlib.h"
#include "internal/nelem.h"
#include "internal/sizes.h"
#include "crypto/rsa.h"
#include "prov/providercommon.h"
#include "prov/implementations.h"
#include "prov/provider_ctx.h"
#include "prov/der_rsa.h"
#include "prov/securitycheck.h"

#define RSA_DEFAULT_DIGEST_NAME OSSL_DIGEST_NAME_SHA1

static OSSL_FUNC_signature_newctx_fn rsa_newctx;
static OSSL_FUNC_signature_sign_init_fn rsa_sign_init;
static OSSL_FUNC_signature_verify_init_fn rsa_verify_init;
static OSSL_FUNC_signature_verify_recover_init_fn rsa_verify_recover_init;
static OSSL_FUNC_signature_sign_fn rsa_sign;
static OSSL_FUNC_signature_verify_fn rsa_verify;
static OSSL_FUNC_signature_verify_recover_fn rsa_verify_recover;
static OSSL_FUNC_signature_digest_sign_init_fn rsa_digest_sign_init;
static OSSL_FUNC_signature_digest_sign_update_fn rsa_digest_signverify_update;
static OSSL_FUNC_signature_digest_sign_final_fn rsa_digest_sign_final;
static OSSL_FUNC_signature_digest_verify_init_fn rsa_digest_verify_init;
static OSSL_FUNC_signature_digest_verify_update_fn rsa_digest_signverify_update;
static OSSL_FUNC_signature_digest_verify_final_fn rsa_digest_verify_final;
static OSSL_FUNC_signature_freectx_fn rsa_freectx;
static OSSL_FUNC_signature_dupctx_fn rsa_dupctx;
static OSSL_FUNC_signature_get_ctx_params_fn rsa_get_ctx_params;
static OSSL_FUNC_signature_gettable_ctx_params_fn rsa_gettable_ctx_params;
static OSSL_FUNC_signature_set_ctx_params_fn rsa_set_ctx_params;
static OSSL_FUNC_signature_settable_ctx_params_fn rsa_settable_ctx_params;
static OSSL_FUNC_signature_get_ctx_md_params_fn rsa_get_ctx_md_params;
static OSSL_FUNC_signature_gettable_ctx_md_params_fn rsa_gettable_ctx_md_params;
static OSSL_FUNC_signature_set_ctx_md_params_fn rsa_set_ctx_md_params;
static OSSL_FUNC_signature_settable_ctx_md_params_fn rsa_settable_ctx_md_params;

static OSSL_ITEM padding_item[] = {
    { RSA_PKCS1_PADDING,        OSSL_PKEY_RSA_PAD_MODE_PKCSV15 },
    { RSA_NO_PADDING,           OSSL_PKEY_RSA_PAD_MODE_NONE },
    { RSA_X931_PADDING,         OSSL_PKEY_RSA_PAD_MODE_X931 },
    { RSA_PKCS1_PSS_PADDING,    OSSL_PKEY_RSA_PAD_MODE_PSS },
    { 0,                        NULL     }
};

/*
 * What's passed as an actual key is defined by the KEYMGMT interface.
 * We happen to know that our KEYMGMT simply passes RSA structures, so
 * we use that here too.
 */

typedef struct {
    OSSL_LIB_CTX *libctx;
    char *propq;
    RSA *rsa;
    int operation;

    /*
     * Flag to determine if the hash function can be changed (1) or not (0)
     * Because it's dangerous to change during a DigestSign or DigestVerify
     * operation, this flag is cleared by their Init function, and set again
     * by their Final function.
     */
    unsigned int flag_allow_md : 1;
    unsigned int mgf1_md_set : 1;

    /* main digest */
    EVP_MD *md;
    EVP_MD_CTX *mdctx;
    int mdnid;
    char mdname[OSSL_MAX_NAME_SIZE]; /* Purely informational */

    /* RSA padding mode */
    int pad_mode;
    /* message digest for MGF1 */
    EVP_MD *mgf1_md;
    int mgf1_mdnid;
    char mgf1_mdname[OSSL_MAX_NAME_SIZE]; /* Purely informational */
    /* PSS salt length */
    int saltlen;
    /* Minimum salt length or -1 if no PSS parameter restriction */
    int min_saltlen;

    /* Temp buffer */
    unsigned char *tbuf;

} PROV_RSA_CTX;

/* True if PSS parameters are restricted */
#define rsa_pss_restricted(prsactx) (prsactx->min_saltlen != -1)

static size_t rsa_get_md_size(const PROV_RSA_CTX *prsactx)
{
    if (prsactx->md != NULL)
        return EVP_MD_get_size(prsactx->md);
    return 0;
}

static int rsa_check_padding(const PROV_RSA_CTX *prsactx,
                             const char *mdname, const char *mgf1_mdname,
                             int mdnid)
{
    switch (prsactx->pad_mode) {
        case RSA_NO_PADDING:
            if (mdname != NULL || mdnid != NID_undef) {
                ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_PADDING_MODE);
                return 0;
            }
            break;
        case RSA_X931_PADDING:
            if (RSA_X931_hash_id(mdnid) == -1) {
                ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_X931_DIGEST);
                return 0;
            }
            break;
        case RSA_PKCS1_PSS_PADDING:
            if (rsa_pss_restricted(prsactx))
                if ((mdname != NULL && !EVP_MD_is_a(prsactx->md, mdname))
                    || (mgf1_mdname != NULL
                        && !EVP_MD_is_a(prsactx->mgf1_md, mgf1_mdname))) {
                    ERR_raise(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED);
                    return 0;
                }
            break;
        default:
            break;
    }

    return 1;
}

static int rsa_check_parameters(PROV_RSA_CTX *prsactx, int min_saltlen)
{
    if (prsactx->pad_mode == RSA_PKCS1_PSS_PADDING) {
        int max_saltlen;

        /* See if minimum salt length exceeds maximum possible */
        max_saltlen = RSA_size(prsactx->rsa) - EVP_MD_get_size(prsactx->md);
        if ((RSA_bits(prsactx->rsa) & 0x7) == 1)
            max_saltlen--;
        if (min_saltlen < 0 || min_saltlen > max_saltlen) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SALT_LENGTH);
            return 0;
        }
        prsactx->min_saltlen = min_saltlen;
    }
    return 1;
}

static void *rsa_newctx(void *provctx, const char *propq)
{
    PROV_RSA_CTX *prsactx = NULL;
    char *propq_copy = NULL;

    if (!ossl_prov_is_running())
        return NULL;

    if ((prsactx = OPENSSL_zalloc(sizeof(PROV_RSA_CTX))) == NULL
        || (propq != NULL
            && (propq_copy = OPENSSL_strdup(propq)) == NULL)) {
        OPENSSL_free(prsactx);
        return NULL;
    }

    prsactx->libctx = PROV_LIBCTX_OF(provctx);
    prsactx->flag_allow_md = 1;
    prsactx->propq = propq_copy;
    /* Maximum up to digest length for sign, auto for verify */
    prsactx->saltlen = RSA_PSS_SALTLEN_AUTO_DIGEST_MAX;
    prsactx->min_saltlen = -1;
    return prsactx;
}

static int rsa_pss_compute_saltlen(PROV_RSA_CTX *ctx)
{
    int saltlen = ctx->saltlen;
    int saltlenMax = -1;

    /* FIPS 186-4 section 5 "The RSA Digital Signature Algorithm", subsection
     * 5.5 "PKCS #1" says: "For RSASSA-PSS […] the length (in bytes) of the
     * salt (sLen) shall satisfy 0 <= sLen <= hLen, where hLen is the length of
     * the hash function output block (in bytes)."
     *
     * Provide a way to use at most the digest length, so that the default does
     * not violate FIPS 186-4. */
    if (saltlen == RSA_PSS_SALTLEN_DIGEST) {
        saltlen = EVP_MD_get_size(ctx->md);
    } else if (saltlen == RSA_PSS_SALTLEN_AUTO_DIGEST_MAX) {
        saltlen = RSA_PSS_SALTLEN_MAX;
        saltlenMax = EVP_MD_get_size(ctx->md);
    }
    if (saltlen == RSA_PSS_SALTLEN_MAX || saltlen == RSA_PSS_SALTLEN_AUTO) {
        saltlen = RSA_size(ctx->rsa) - EVP_MD_get_size(ctx->md) - 2;
        if ((RSA_bits(ctx->rsa) & 0x7) == 1)
            saltlen--;
        if (saltlenMax >= 0 && saltlen > saltlenMax)
            saltlen = saltlenMax;
    }
    if (saltlen < 0) {
        ERR_raise(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR);
        return -1;
    } else if (saltlen < ctx->min_saltlen) {
        ERR_raise_data(ERR_LIB_PROV, PROV_R_PSS_SALTLEN_TOO_SMALL,
                       "minimum salt length: %d, actual salt length: %d",
                       ctx->min_saltlen, saltlen);
        return -1;
    }
    return saltlen;
}

static unsigned char *rsa_generate_signature_aid(PROV_RSA_CTX *ctx,
                                                 unsigned char *aid_buf,
                                                 size_t buf_len,
                                                 size_t *aid_len)
{
    WPACKET pkt;
    unsigned char *aid = NULL;
    int saltlen;
    RSA_PSS_PARAMS_30 pss_params;
    int ret;

    if (!WPACKET_init_der(&pkt, aid_buf, buf_len)) {
        ERR_raise(ERR_LIB_PROV, ERR_R_CRYPTO_LIB);
        return NULL;
    }

    switch (ctx->pad_mode) {
    case RSA_PKCS1_PADDING:
        ret = ossl_DER_w_algorithmIdentifier_MDWithRSAEncryption(&pkt, -1,
                                                                 ctx->mdnid);

        if (ret > 0) {
            break;
        } else if (ret == 0) {
            ERR_raise(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR);
            goto cleanup;
        }
        ERR_raise_data(ERR_LIB_PROV, ERR_R_UNSUPPORTED,
                       "Algorithm ID generation - md NID: %d",
                       ctx->mdnid);
        goto cleanup;
    case RSA_PKCS1_PSS_PADDING:
        saltlen = rsa_pss_compute_saltlen(ctx);
        if (saltlen < 0)
            goto cleanup;
        if (!ossl_rsa_pss_params_30_set_defaults(&pss_params)
            || !ossl_rsa_pss_params_30_set_hashalg(&pss_params, ctx->mdnid)
            || !ossl_rsa_pss_params_30_set_maskgenhashalg(&pss_params,
                                                          ctx->mgf1_mdnid)
            || !ossl_rsa_pss_params_30_set_saltlen(&pss_params, saltlen)
            || !ossl_DER_w_algorithmIdentifier_RSA_PSS(&pkt, -1,
                                                       RSA_FLAG_TYPE_RSASSAPSS,
                                                       &pss_params)) {
            ERR_raise(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR);
            goto cleanup;
        }
        break;
    default:
        ERR_raise_data(ERR_LIB_PROV, ERR_R_UNSUPPORTED,
                       "Algorithm ID generation - pad mode: %d",
                       ctx->pad_mode);
        goto cleanup;
    }
    if (WPACKET_finish(&pkt)) {
        WPACKET_get_total_written(&pkt, aid_len);
        aid = WPACKET_get_curr(&pkt);
    }
 cleanup:
    WPACKET_cleanup(&pkt);
    return aid;
}

static int rsa_setup_md(PROV_RSA_CTX *ctx, const char *mdname,
                        const char *mdprops)
{
    if (mdprops == NULL)
        mdprops = ctx->propq;

    if (mdname != NULL) {
        EVP_MD *md = EVP_MD_fetch(ctx->libctx, mdname, mdprops);
        int sha1_allowed = (ctx->operation != EVP_PKEY_OP_SIGN);
        int md_nid = ossl_digest_rsa_sign_get_md_nid(ctx->libctx, md,
                                                     sha1_allowed);
        size_t mdname_len = strlen(mdname);

        if (md == NULL
            || md_nid <= 0
            || !rsa_check_padding(ctx, mdname, NULL, md_nid)
            || mdname_len >= sizeof(ctx->mdname)) {
            if (md == NULL)
                ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                               "%s could not be fetched", mdname);
            if (md_nid <= 0)
                ERR_raise_data(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED,
                               "digest=%s", mdname);
            if (mdname_len >= sizeof(ctx->mdname))
                ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                               "%s exceeds name buffer length", mdname);
            EVP_MD_free(md);
            return 0;
        }

        if (!ctx->flag_allow_md) {
            if (ctx->mdname[0] != '\0' && !EVP_MD_is_a(md, ctx->mdname)) {
                ERR_raise_data(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED,
                               "digest %s != %s", mdname, ctx->mdname);
                EVP_MD_free(md);
                return 0;
            }
            EVP_MD_free(md);
            return 1;
        }

        if (!ctx->mgf1_md_set) {
            if (!EVP_MD_up_ref(md)) {
                EVP_MD_free(md);
                return 0;
            }
            EVP_MD_free(ctx->mgf1_md);
            ctx->mgf1_md = md;
            ctx->mgf1_mdnid = md_nid;
            OPENSSL_strlcpy(ctx->mgf1_mdname, mdname, sizeof(ctx->mgf1_mdname));
        }

        EVP_MD_CTX_free(ctx->mdctx);
        EVP_MD_free(ctx->md);

        ctx->mdctx = NULL;
        ctx->md = md;
        ctx->mdnid = md_nid;
        OPENSSL_strlcpy(ctx->mdname, mdname, sizeof(ctx->mdname));
    }

    return 1;
}

static int rsa_setup_mgf1_md(PROV_RSA_CTX *ctx, const char *mdname,
                             const char *mdprops)
{
    size_t len;
    EVP_MD *md = NULL;
    int mdnid;

    if (mdprops == NULL)
        mdprops = ctx->propq;

    if ((md = EVP_MD_fetch(ctx->libctx, mdname, mdprops)) == NULL) {
        ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                       "%s could not be fetched", mdname);
        return 0;
    }
    /* The default for mgf1 is SHA1 - so allow SHA1 */
    if ((mdnid = ossl_digest_rsa_sign_get_md_nid(ctx->libctx, md, 1)) <= 0
        || !rsa_check_padding(ctx, NULL, mdname, mdnid)) {
        if (mdnid <= 0)
            ERR_raise_data(ERR_LIB_PROV, PROV_R_DIGEST_NOT_ALLOWED,
                           "digest=%s", mdname);
        EVP_MD_free(md);
        return 0;
    }
    len = OPENSSL_strlcpy(ctx->mgf1_mdname, mdname, sizeof(ctx->mgf1_mdname));
    if (len >= sizeof(ctx->mgf1_mdname)) {
        ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                       "%s exceeds name buffer length", mdname);
        EVP_MD_free(md);
        return 0;
    }

    EVP_MD_free(ctx->mgf1_md);
    ctx->mgf1_md = md;
    ctx->mgf1_mdnid = mdnid;
    ctx->mgf1_md_set = 1;
    return 1;
}

static int rsa_signverify_init(void *vprsactx, void *vrsa,
                               const OSSL_PARAM params[], int operation)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (!ossl_prov_is_running() || prsactx == NULL)
        return 0;

    if (vrsa == NULL && prsactx->rsa == NULL) {
        ERR_raise(ERR_LIB_PROV, PROV_R_NO_KEY_SET);
        return 0;
    }

    if (vrsa != NULL) {
        if (!ossl_rsa_check_key(prsactx->libctx, vrsa, operation))
            return 0;

        if (!RSA_up_ref(vrsa))
            return 0;
        RSA_free(prsactx->rsa);
        prsactx->rsa = vrsa;
    }

    prsactx->operation = operation;

    /* Maximize up to digest length for sign, auto for verify */
    prsactx->saltlen = RSA_PSS_SALTLEN_AUTO_DIGEST_MAX;
    prsactx->min_saltlen = -1;

    switch (RSA_test_flags(prsactx->rsa, RSA_FLAG_TYPE_MASK)) {
    case RSA_FLAG_TYPE_RSA:
        prsactx->pad_mode = RSA_PKCS1_PADDING;
        break;
    case RSA_FLAG_TYPE_RSASSAPSS:
        prsactx->pad_mode = RSA_PKCS1_PSS_PADDING;

        {
            const RSA_PSS_PARAMS_30 *pss =
                ossl_rsa_get0_pss_params_30(prsactx->rsa);

            if (!ossl_rsa_pss_params_30_is_unrestricted(pss)) {
                int md_nid = ossl_rsa_pss_params_30_hashalg(pss);
                int mgf1md_nid = ossl_rsa_pss_params_30_maskgenhashalg(pss);
                int min_saltlen = ossl_rsa_pss_params_30_saltlen(pss);
                const char *mdname, *mgf1mdname;
                size_t len;

                mdname = ossl_rsa_oaeppss_nid2name(md_nid);
                mgf1mdname = ossl_rsa_oaeppss_nid2name(mgf1md_nid);

                if (mdname == NULL) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                                   "PSS restrictions lack hash algorithm");
                    return 0;
                }
                if (mgf1mdname == NULL) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                                   "PSS restrictions lack MGF1 hash algorithm");
                    return 0;
                }

                len = OPENSSL_strlcpy(prsactx->mdname, mdname,
                                      sizeof(prsactx->mdname));
                if (len >= sizeof(prsactx->mdname)) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                                   "hash algorithm name too long");
                    return 0;
                }
                len = OPENSSL_strlcpy(prsactx->mgf1_mdname, mgf1mdname,
                                      sizeof(prsactx->mgf1_mdname));
                if (len >= sizeof(prsactx->mgf1_mdname)) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST,
                                   "MGF1 hash algorithm name too long");
                    return 0;
                }
                prsactx->saltlen = min_saltlen;

                /* call rsa_setup_mgf1_md before rsa_setup_md to avoid duplication */
                if (!rsa_setup_mgf1_md(prsactx, mgf1mdname, prsactx->propq)
                    || !rsa_setup_md(prsactx, mdname, prsactx->propq)
                    || !rsa_check_parameters(prsactx, min_saltlen))
                    return 0;
            }
        }

        break;
    default:
        ERR_raise(ERR_LIB_RSA, PROV_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
        return 0;
    }

    if (!rsa_set_ctx_params(prsactx, params))
        return 0;

    return 1;
}

static int setup_tbuf(PROV_RSA_CTX *ctx)
{
    if (ctx->tbuf != NULL)
        return 1;
    if ((ctx->tbuf = OPENSSL_malloc(RSA_size(ctx->rsa))) == NULL)
        return 0;
    return 1;
}

static void clean_tbuf(PROV_RSA_CTX *ctx)
{
    if (ctx->tbuf != NULL)
        OPENSSL_cleanse(ctx->tbuf, RSA_size(ctx->rsa));
}

static void free_tbuf(PROV_RSA_CTX *ctx)
{
    clean_tbuf(ctx);
    OPENSSL_free(ctx->tbuf);
    ctx->tbuf = NULL;
}

static int rsa_sign_init(void *vprsactx, void *vrsa, const OSSL_PARAM params[])
{
    if (!ossl_prov_is_running())
        return 0;
    return rsa_signverify_init(vprsactx, vrsa, params, EVP_PKEY_OP_SIGN);
}

static int rsa_sign(void *vprsactx, unsigned char *sig, size_t *siglen,
                    size_t sigsize, const unsigned char *tbs, size_t tbslen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    int ret;
    size_t rsasize = RSA_size(prsactx->rsa);
    size_t mdsize = rsa_get_md_size(prsactx);

    if (!ossl_prov_is_running())
        return 0;

    if (sig == NULL) {
        *siglen = rsasize;
        return 1;
    }

    if (sigsize < rsasize) {
        ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_SIGNATURE_SIZE,
                       "is %zu, should be at least %zu", sigsize, rsasize);
        return 0;
    }

    if (mdsize != 0) {
        if (tbslen != mdsize) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_DIGEST_LENGTH);
            return 0;
        }

#ifndef FIPS_MODULE
        if (EVP_MD_is_a(prsactx->md, OSSL_DIGEST_NAME_MDC2)) {
            unsigned int sltmp;

            if (prsactx->pad_mode != RSA_PKCS1_PADDING) {
                ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_PADDING_MODE,
                               "only PKCS#1 padding supported with MDC2");
                return 0;
            }
            ret = RSA_sign_ASN1_OCTET_STRING(0, tbs, tbslen, sig, &sltmp,
                                             prsactx->rsa);

            if (ret <= 0) {
                ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                return 0;
            }
            ret = sltmp;
            goto end;
        }
#endif
        switch (prsactx->pad_mode) {
        case RSA_X931_PADDING:
            if ((size_t)RSA_size(prsactx->rsa) < tbslen + 1) {
                ERR_raise_data(ERR_LIB_PROV, PROV_R_KEY_SIZE_TOO_SMALL,
                               "RSA key size = %d, expected minimum = %d",
                               RSA_size(prsactx->rsa), tbslen + 1);
                return 0;
            }
            if (!setup_tbuf(prsactx)) {
                ERR_raise(ERR_LIB_PROV, ERR_R_PROV_LIB);
                return 0;
            }
            memcpy(prsactx->tbuf, tbs, tbslen);
            prsactx->tbuf[tbslen] = RSA_X931_hash_id(prsactx->mdnid);
            ret = RSA_private_encrypt(tbslen + 1, prsactx->tbuf,
                                      sig, prsactx->rsa, RSA_X931_PADDING);
            clean_tbuf(prsactx);
            break;

        case RSA_PKCS1_PADDING:
            {
                unsigned int sltmp;

                ret = RSA_sign(prsactx->mdnid, tbs, tbslen, sig, &sltmp,
                               prsactx->rsa);
                if (ret <= 0) {
                    ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                    return 0;
                }
                ret = sltmp;
            }
            break;

        case RSA_PKCS1_PSS_PADDING:
            /* Check PSS restrictions */
            if (rsa_pss_restricted(prsactx)) {
                switch (prsactx->saltlen) {
                case RSA_PSS_SALTLEN_DIGEST:
                    if (prsactx->min_saltlen > EVP_MD_get_size(prsactx->md)) {
                        ERR_raise_data(ERR_LIB_PROV,
                                       PROV_R_PSS_SALTLEN_TOO_SMALL,
                                       "minimum salt length set to %d, "
                                       "but the digest only gives %d",
                                       prsactx->min_saltlen,
                                       EVP_MD_get_size(prsactx->md));
                        return 0;
                    }
                    /* FALLTHRU */
                default:
                    if (prsactx->saltlen >= 0
                        && prsactx->saltlen < prsactx->min_saltlen) {
                        ERR_raise_data(ERR_LIB_PROV,
                                       PROV_R_PSS_SALTLEN_TOO_SMALL,
                                       "minimum salt length set to %d, but the"
                                       "actual salt length is only set to %d",
                                       prsactx->min_saltlen,
                                       prsactx->saltlen);
                        return 0;
                    }
                    break;
                }
            }
            if (!setup_tbuf(prsactx))
                return 0;
            if (!RSA_padding_add_PKCS1_PSS_mgf1(prsactx->rsa,
                                                prsactx->tbuf, tbs,
                                                prsactx->md, prsactx->mgf1_md,
                                                prsactx->saltlen)) {
                ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                return 0;
            }
            ret = RSA_private_encrypt(RSA_size(prsactx->rsa), prsactx->tbuf,
                                      sig, prsactx->rsa, RSA_NO_PADDING);
            clean_tbuf(prsactx);
            break;

        default:
            ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_PADDING_MODE,
                           "Only X.931, PKCS#1 v1.5 or PSS padding allowed");
            return 0;
        }
    } else {
        ret = RSA_private_encrypt(tbslen, tbs, sig, prsactx->rsa,
                                  prsactx->pad_mode);
    }

#ifndef FIPS_MODULE
 end:
#endif
    if (ret <= 0) {
        ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
        return 0;
    }

    *siglen = ret;
    return 1;
}

static int rsa_verify_recover_init(void *vprsactx, void *vrsa,
                                   const OSSL_PARAM params[])
{
    if (!ossl_prov_is_running())
        return 0;
    return rsa_signverify_init(vprsactx, vrsa, params,
                               EVP_PKEY_OP_VERIFYRECOVER);
}

static int rsa_verify_recover(void *vprsactx,
                              unsigned char *rout,
                              size_t *routlen,
                              size_t routsize,
                              const unsigned char *sig,
                              size_t siglen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    int ret;

    if (!ossl_prov_is_running())
        return 0;

    if (rout == NULL) {
        *routlen = RSA_size(prsactx->rsa);
        return 1;
    }

    if (prsactx->md != NULL) {
        switch (prsactx->pad_mode) {
        case RSA_X931_PADDING:
            if (!setup_tbuf(prsactx))
                return 0;
            ret = RSA_public_decrypt(siglen, sig, prsactx->tbuf, prsactx->rsa,
                                     RSA_X931_PADDING);
            if (ret < 1) {
                ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                return 0;
            }
            ret--;
            if (prsactx->tbuf[ret] != RSA_X931_hash_id(prsactx->mdnid)) {
                ERR_raise(ERR_LIB_PROV, PROV_R_ALGORITHM_MISMATCH);
                return 0;
            }
            if (ret != EVP_MD_get_size(prsactx->md)) {
                ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST_LENGTH,
                               "Should be %d, but got %d",
                               EVP_MD_get_size(prsactx->md), ret);
                return 0;
            }

            *routlen = ret;
            if (rout != prsactx->tbuf) {
                if (routsize < (size_t)ret) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_OUTPUT_BUFFER_TOO_SMALL,
                                   "buffer size is %d, should be %d",
                                   routsize, ret);
                    return 0;
                }
                memcpy(rout, prsactx->tbuf, ret);
            }
            break;

        case RSA_PKCS1_PADDING:
            {
                size_t sltmp;

                ret = ossl_rsa_verify(prsactx->mdnid, NULL, 0, rout, &sltmp,
                                      sig, siglen, prsactx->rsa);
                if (ret <= 0) {
                    ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                    return 0;
                }
                ret = sltmp;
            }
            break;

        default:
            ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_PADDING_MODE,
                           "Only X.931 or PKCS#1 v1.5 padding allowed");
            return 0;
        }
    } else {
        ret = RSA_public_decrypt(siglen, sig, rout, prsactx->rsa,
                                 prsactx->pad_mode);
        if (ret < 0) {
            ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
            return 0;
        }
    }
    *routlen = ret;
    return 1;
}

static int rsa_verify_init(void *vprsactx, void *vrsa,
                           const OSSL_PARAM params[])
{
    if (!ossl_prov_is_running())
        return 0;
    return rsa_signverify_init(vprsactx, vrsa, params, EVP_PKEY_OP_VERIFY);
}

static int rsa_verify(void *vprsactx, const unsigned char *sig, size_t siglen,
                      const unsigned char *tbs, size_t tbslen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    size_t rslen;

    if (!ossl_prov_is_running())
        return 0;
    if (prsactx->md != NULL) {
        switch (prsactx->pad_mode) {
        case RSA_PKCS1_PADDING:
            if (!RSA_verify(prsactx->mdnid, tbs, tbslen, sig, siglen,
                            prsactx->rsa)) {
                ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                return 0;
            }
            return 1;
        case RSA_X931_PADDING:
            if (!setup_tbuf(prsactx))
                return 0;
            if (rsa_verify_recover(prsactx, prsactx->tbuf, &rslen, 0,
                                   sig, siglen) <= 0)
                return 0;
            break;
        case RSA_PKCS1_PSS_PADDING:
            {
                int ret;
                size_t mdsize;

                /*
                 * We need to check this for the RSA_verify_PKCS1_PSS_mgf1()
                 * call
                 */
                mdsize = rsa_get_md_size(prsactx);
                if (tbslen != mdsize) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_DIGEST_LENGTH,
                                   "Should be %d, but got %d",
                                   mdsize, tbslen);
                    return 0;
                }

                if (!setup_tbuf(prsactx))
                    return 0;
                ret = RSA_public_decrypt(siglen, sig, prsactx->tbuf,
                                         prsactx->rsa, RSA_NO_PADDING);
                if (ret <= 0) {
                    ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                    return 0;
                }
                ret = RSA_verify_PKCS1_PSS_mgf1(prsactx->rsa, tbs,
                                                prsactx->md, prsactx->mgf1_md,
                                                prsactx->tbuf,
                                                prsactx->saltlen);
                if (ret <= 0) {
                    ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
                    return 0;
                }
                return 1;
            }
        default:
            ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_PADDING_MODE,
                           "Only X.931, PKCS#1 v1.5 or PSS padding allowed");
            return 0;
        }
    } else {
        int ret;

        if (!setup_tbuf(prsactx))
            return 0;
        ret = RSA_public_decrypt(siglen, sig, prsactx->tbuf, prsactx->rsa,
                                 prsactx->pad_mode);
        if (ret <= 0) {
            ERR_raise(ERR_LIB_PROV, ERR_R_RSA_LIB);
            return 0;
        }
        rslen = (size_t)ret;
    }

    if ((rslen != tbslen) || memcmp(tbs, prsactx->tbuf, rslen))
        return 0;

    return 1;
}

static int rsa_digest_signverify_init(void *vprsactx, const char *mdname,
                                      void *vrsa, const OSSL_PARAM params[],
                                      int operation)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (!ossl_prov_is_running())
        return 0;

    if (!rsa_signverify_init(vprsactx, vrsa, params, operation))
        return 0;

    if (mdname != NULL
        /* was rsa_setup_md already called in rsa_signverify_init()? */
        && (mdname[0] == '\0' || OPENSSL_strcasecmp(prsactx->mdname, mdname) != 0)
        && !rsa_setup_md(prsactx, mdname, prsactx->propq))
        return 0;

    prsactx->flag_allow_md = 0;

    if (prsactx->mdctx == NULL) {
        prsactx->mdctx = EVP_MD_CTX_new();
        if (prsactx->mdctx == NULL)
            goto error;
    }

    if (!EVP_DigestInit_ex2(prsactx->mdctx, prsactx->md, params))
        goto error;

    return 1;

 error:
    EVP_MD_CTX_free(prsactx->mdctx);
    prsactx->mdctx = NULL;
    return 0;
}

static int rsa_digest_signverify_update(void *vprsactx,
                                        const unsigned char *data,
                                        size_t datalen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx == NULL || prsactx->mdctx == NULL)
        return 0;

    return EVP_DigestUpdate(prsactx->mdctx, data, datalen);
}

static int rsa_digest_sign_init(void *vprsactx, const char *mdname,
                                void *vrsa, const OSSL_PARAM params[])
{
    if (!ossl_prov_is_running())
        return 0;
    return rsa_digest_signverify_init(vprsactx, mdname, vrsa,
                                      params, EVP_PKEY_OP_SIGN);
}

static int rsa_digest_sign_final(void *vprsactx, unsigned char *sig,
                                 size_t *siglen, size_t sigsize)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    unsigned char digest[EVP_MAX_MD_SIZE];
    unsigned int dlen = 0;

    if (!ossl_prov_is_running() || prsactx == NULL)
        return 0;
    prsactx->flag_allow_md = 1;
    if (prsactx->mdctx == NULL)
        return 0;
    /*
     * If sig is NULL then we're just finding out the sig size. Other fields
     * are ignored. Defer to rsa_sign.
     */
    if (sig != NULL) {
        /*
         * The digests used here are all known (see rsa_get_md_nid()), so they
         * should not exceed the internal buffer size of EVP_MAX_MD_SIZE.
         */
        if (!EVP_DigestFinal_ex(prsactx->mdctx, digest, &dlen))
            return 0;
    }

    return rsa_sign(vprsactx, sig, siglen, sigsize, digest, (size_t)dlen);
}

static int rsa_digest_verify_init(void *vprsactx, const char *mdname,
                                  void *vrsa, const OSSL_PARAM params[])
{
    if (!ossl_prov_is_running())
        return 0;
    return rsa_digest_signverify_init(vprsactx, mdname, vrsa,
                                      params, EVP_PKEY_OP_VERIFY);
}

int rsa_digest_verify_final(void *vprsactx, const unsigned char *sig,
                            size_t siglen)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    unsigned char digest[EVP_MAX_MD_SIZE];
    unsigned int dlen = 0;

    if (!ossl_prov_is_running())
        return 0;

    if (prsactx == NULL)
        return 0;
    prsactx->flag_allow_md = 1;
    if (prsactx->mdctx == NULL)
        return 0;

    /*
     * The digests used here are all known (see rsa_get_md_nid()), so they
     * should not exceed the internal buffer size of EVP_MAX_MD_SIZE.
     */
    if (!EVP_DigestFinal_ex(prsactx->mdctx, digest, &dlen))
        return 0;

    return rsa_verify(vprsactx, sig, siglen, digest, (size_t)dlen);
}

static void rsa_freectx(void *vprsactx)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx == NULL)
        return;

    EVP_MD_CTX_free(prsactx->mdctx);
    EVP_MD_free(prsactx->md);
    EVP_MD_free(prsactx->mgf1_md);
    OPENSSL_free(prsactx->propq);
    free_tbuf(prsactx);
    RSA_free(prsactx->rsa);

    OPENSSL_clear_free(prsactx, sizeof(*prsactx));
}

static void *rsa_dupctx(void *vprsactx)
{
    PROV_RSA_CTX *srcctx = (PROV_RSA_CTX *)vprsactx;
    PROV_RSA_CTX *dstctx;

    if (!ossl_prov_is_running())
        return NULL;

    dstctx = OPENSSL_zalloc(sizeof(*srcctx));
    if (dstctx == NULL)
        return NULL;

    *dstctx = *srcctx;
    dstctx->rsa = NULL;
    dstctx->md = NULL;
    dstctx->mdctx = NULL;
    dstctx->tbuf = NULL;
    dstctx->propq = NULL;

    if (srcctx->rsa != NULL && !RSA_up_ref(srcctx->rsa))
        goto err;
    dstctx->rsa = srcctx->rsa;

    if (srcctx->md != NULL && !EVP_MD_up_ref(srcctx->md))
        goto err;
    dstctx->md = srcctx->md;

    if (srcctx->mgf1_md != NULL && !EVP_MD_up_ref(srcctx->mgf1_md))
        goto err;
    dstctx->mgf1_md = srcctx->mgf1_md;

    if (srcctx->mdctx != NULL) {
        dstctx->mdctx = EVP_MD_CTX_new();
        if (dstctx->mdctx == NULL
                || !EVP_MD_CTX_copy_ex(dstctx->mdctx, srcctx->mdctx))
            goto err;
    }

    if (srcctx->propq != NULL) {
        dstctx->propq = OPENSSL_strdup(srcctx->propq);
        if (dstctx->propq == NULL)
            goto err;
    }

    return dstctx;
 err:
    rsa_freectx(dstctx);
    return NULL;
}

static int rsa_get_ctx_params(void *vprsactx, OSSL_PARAM *params)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    OSSL_PARAM *p;

    if (prsactx == NULL)
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_ALGORITHM_ID);
    if (p != NULL) {
        /* The Algorithm Identifier of the combined signature algorithm */
        unsigned char aid_buf[128];
        unsigned char *aid;
        size_t  aid_len;

        aid = rsa_generate_signature_aid(prsactx, aid_buf,
                                         sizeof(aid_buf), &aid_len);
        if (aid == NULL || !OSSL_PARAM_set_octet_string(p, aid, aid_len))
            return 0;
    }

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_PAD_MODE);
    if (p != NULL)
        switch (p->data_type) {
        case OSSL_PARAM_INTEGER:
            if (!OSSL_PARAM_set_int(p, prsactx->pad_mode))
                return 0;
            break;
        case OSSL_PARAM_UTF8_STRING:
            {
                int i;
                const char *word = NULL;

                for (i = 0; padding_item[i].id != 0; i++) {
                    if (prsactx->pad_mode == (int)padding_item[i].id) {
                        word = padding_item[i].ptr;
                        break;
                    }
                }

                if (word != NULL) {
                    if (!OSSL_PARAM_set_utf8_string(p, word))
                        return 0;
                } else {
                    ERR_raise(ERR_LIB_PROV, ERR_R_INTERNAL_ERROR);
                }
            }
            break;
        default:
            return 0;
        }

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_DIGEST);
    if (p != NULL && !OSSL_PARAM_set_utf8_string(p, prsactx->mdname))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_MGF1_DIGEST);
    if (p != NULL && !OSSL_PARAM_set_utf8_string(p, prsactx->mgf1_mdname))
        return 0;

    p = OSSL_PARAM_locate(params, OSSL_SIGNATURE_PARAM_PSS_SALTLEN);
    if (p != NULL) {
        if (p->data_type == OSSL_PARAM_INTEGER) {
            if (!OSSL_PARAM_set_int(p, prsactx->saltlen))
                return 0;
        } else if (p->data_type == OSSL_PARAM_UTF8_STRING) {
            const char *value = NULL;

            switch (prsactx->saltlen) {
            case RSA_PSS_SALTLEN_DIGEST:
                value = OSSL_PKEY_RSA_PSS_SALT_LEN_DIGEST;
                break;
            case RSA_PSS_SALTLEN_MAX:
                value = OSSL_PKEY_RSA_PSS_SALT_LEN_MAX;
                break;
            case RSA_PSS_SALTLEN_AUTO:
                value = OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO;
                break;
            case RSA_PSS_SALTLEN_AUTO_DIGEST_MAX:
                value = OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO_DIGEST_MAX;
                break;
            default:
                {
                    int len = BIO_snprintf(p->data, p->data_size, "%d",
                                           prsactx->saltlen);

                    if (len <= 0)
                        return 0;
                    p->return_size = len;
                    break;
                }
            }
            if (value != NULL
                && !OSSL_PARAM_set_utf8_string(p, value))
                return 0;
        }
    }

    return 1;
}

static const OSSL_PARAM known_gettable_ctx_params[] = {
    OSSL_PARAM_octet_string(OSSL_SIGNATURE_PARAM_ALGORITHM_ID, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0),
    OSSL_PARAM_END
};

static const OSSL_PARAM *rsa_gettable_ctx_params(ossl_unused void *vprsactx,
                                                 ossl_unused void *provctx)
{
    return known_gettable_ctx_params;
}

static int rsa_set_ctx_params(void *vprsactx, const OSSL_PARAM params[])
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;
    const OSSL_PARAM *p;
    int pad_mode;
    int saltlen;
    char mdname[OSSL_MAX_NAME_SIZE] = "", *pmdname = NULL;
    char mdprops[OSSL_MAX_PROPQUERY_SIZE] = "", *pmdprops = NULL;
    char mgf1mdname[OSSL_MAX_NAME_SIZE] = "", *pmgf1mdname = NULL;
    char mgf1mdprops[OSSL_MAX_PROPQUERY_SIZE] = "", *pmgf1mdprops = NULL;

    if (prsactx == NULL)
        return 0;
    if (params == NULL)
        return 1;

    pad_mode = prsactx->pad_mode;
    saltlen = prsactx->saltlen;

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_DIGEST);
    if (p != NULL) {
        const OSSL_PARAM *propsp =
            OSSL_PARAM_locate_const(params,
                                    OSSL_SIGNATURE_PARAM_PROPERTIES);

        pmdname = mdname;
        if (!OSSL_PARAM_get_utf8_string(p, &pmdname, sizeof(mdname)))
            return 0;

        if (propsp != NULL) {
            pmdprops = mdprops;
            if (!OSSL_PARAM_get_utf8_string(propsp,
                                            &pmdprops, sizeof(mdprops)))
                return 0;
        }
    }

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_PAD_MODE);
    if (p != NULL) {
        const char *err_extra_text = NULL;

        switch (p->data_type) {
        case OSSL_PARAM_INTEGER: /* Support for legacy pad mode number */
            if (!OSSL_PARAM_get_int(p, &pad_mode))
                return 0;
            break;
        case OSSL_PARAM_UTF8_STRING:
            {
                int i;

                if (p->data == NULL)
                    return 0;

                for (i = 0; padding_item[i].id != 0; i++) {
                    if (strcmp(p->data, padding_item[i].ptr) == 0) {
                        pad_mode = padding_item[i].id;
                        break;
                    }
                }
            }
            break;
        default:
            return 0;
        }

        switch (pad_mode) {
        case RSA_PKCS1_OAEP_PADDING:
            /*
             * OAEP padding is for asymmetric cipher only so is not compatible
             * with signature use.
             */
            err_extra_text = "OAEP padding not allowed for signing / verifying";
            goto bad_pad;
        case RSA_PKCS1_PSS_PADDING:
            if ((prsactx->operation
                 & (EVP_PKEY_OP_SIGN | EVP_PKEY_OP_VERIFY)) == 0) {
                err_extra_text =
                    "PSS padding only allowed for sign and verify operations";
                goto bad_pad;
            }
            break;
        case RSA_PKCS1_PADDING:
            err_extra_text = "PKCS#1 padding not allowed with RSA-PSS";
            goto cont;
        case RSA_NO_PADDING:
            err_extra_text = "No padding not allowed with RSA-PSS";
            goto cont;
        case RSA_X931_PADDING:
            err_extra_text = "X.931 padding not allowed with RSA-PSS";
        cont:
            if (RSA_test_flags(prsactx->rsa,
                               RSA_FLAG_TYPE_MASK) == RSA_FLAG_TYPE_RSA)
                break;
            /* FALLTHRU */
        default:
        bad_pad:
            if (err_extra_text == NULL)
                ERR_raise(ERR_LIB_PROV,
                          PROV_R_ILLEGAL_OR_UNSUPPORTED_PADDING_MODE);
            else
                ERR_raise_data(ERR_LIB_PROV,
                               PROV_R_ILLEGAL_OR_UNSUPPORTED_PADDING_MODE,
                               err_extra_text);
            return 0;
        }
    }

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_PSS_SALTLEN);
    if (p != NULL) {
        if (pad_mode != RSA_PKCS1_PSS_PADDING) {
            ERR_raise_data(ERR_LIB_PROV, PROV_R_NOT_SUPPORTED,
                           "PSS saltlen can only be specified if "
                           "PSS padding has been specified first");
            return 0;
        }

        switch (p->data_type) {
        case OSSL_PARAM_INTEGER: /* Support for legacy pad mode number */
            if (!OSSL_PARAM_get_int(p, &saltlen))
                return 0;
            break;
        case OSSL_PARAM_UTF8_STRING:
            if (strcmp(p->data, OSSL_PKEY_RSA_PSS_SALT_LEN_DIGEST) == 0)
                saltlen = RSA_PSS_SALTLEN_DIGEST;
            else if (strcmp(p->data, OSSL_PKEY_RSA_PSS_SALT_LEN_MAX) == 0)
                saltlen = RSA_PSS_SALTLEN_MAX;
            else if (strcmp(p->data, OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO) == 0)
                saltlen = RSA_PSS_SALTLEN_AUTO;
            else if (strcmp(p->data, OSSL_PKEY_RSA_PSS_SALT_LEN_AUTO_DIGEST_MAX) == 0)
                saltlen = RSA_PSS_SALTLEN_AUTO_DIGEST_MAX;
            else
                saltlen = atoi(p->data);
            break;
        default:
            return 0;
        }

        /*
         * RSA_PSS_SALTLEN_AUTO_DIGEST_MAX seems curiously named in this check.
         * Contrary to what it's name suggests, it's the currently lowest
         * saltlen number possible.
         */
        if (saltlen < RSA_PSS_SALTLEN_AUTO_DIGEST_MAX) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_SALT_LENGTH);
            return 0;
        }

        if (rsa_pss_restricted(prsactx)) {
            switch (saltlen) {
            case RSA_PSS_SALTLEN_AUTO:
            case RSA_PSS_SALTLEN_AUTO_DIGEST_MAX:
                if (prsactx->operation == EVP_PKEY_OP_VERIFY) {
                    ERR_raise_data(ERR_LIB_PROV, PROV_R_INVALID_SALT_LENGTH,
                                   "Cannot use autodetected salt length");
                    return 0;
                }
                break;
            case RSA_PSS_SALTLEN_DIGEST:
                if (prsactx->min_saltlen > EVP_MD_get_size(prsactx->md)) {
                    ERR_raise_data(ERR_LIB_PROV,
                                   PROV_R_PSS_SALTLEN_TOO_SMALL,
                                   "Should be more than %d, but would be "
                                   "set to match digest size (%d)",
                                   prsactx->min_saltlen,
                                   EVP_MD_get_size(prsactx->md));
                    return 0;
                }
                break;
            default:
                if (saltlen >= 0 && saltlen < prsactx->min_saltlen) {
                    ERR_raise_data(ERR_LIB_PROV,
                                   PROV_R_PSS_SALTLEN_TOO_SMALL,
                                   "Should be more than %d, "
                                   "but would be set to %d",
                                   prsactx->min_saltlen, saltlen);
                    return 0;
                }
            }
        }
    }

    p = OSSL_PARAM_locate_const(params, OSSL_SIGNATURE_PARAM_MGF1_DIGEST);
    if (p != NULL) {
        const OSSL_PARAM *propsp =
            OSSL_PARAM_locate_const(params,
                                    OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES);

        pmgf1mdname = mgf1mdname;
        if (!OSSL_PARAM_get_utf8_string(p, &pmgf1mdname, sizeof(mgf1mdname)))
            return 0;

        if (propsp != NULL) {
            pmgf1mdprops = mgf1mdprops;
            if (!OSSL_PARAM_get_utf8_string(propsp,
                                            &pmgf1mdprops, sizeof(mgf1mdprops)))
                return 0;
        }

        if (pad_mode != RSA_PKCS1_PSS_PADDING) {
            ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MGF1_MD);
            return  0;
        }
    }

    prsactx->saltlen = saltlen;
    prsactx->pad_mode = pad_mode;

    if (prsactx->md == NULL && pmdname == NULL
        && pad_mode == RSA_PKCS1_PSS_PADDING)
        pmdname = RSA_DEFAULT_DIGEST_NAME;

    if (pmgf1mdname != NULL
        && !rsa_setup_mgf1_md(prsactx, pmgf1mdname, pmgf1mdprops))
        return 0;

    if (pmdname != NULL) {
        if (!rsa_setup_md(prsactx, pmdname, pmdprops))
            return 0;
    } else {
        if (!rsa_check_padding(prsactx, NULL, NULL, prsactx->mdnid))
            return 0;
    }
    return 1;
}

static const OSSL_PARAM settable_ctx_params[] = {
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PROPERTIES, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0),
    OSSL_PARAM_END
};

static const OSSL_PARAM settable_ctx_params_no_digest[] = {
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PAD_MODE, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_DIGEST, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_MGF1_PROPERTIES, NULL, 0),
    OSSL_PARAM_utf8_string(OSSL_SIGNATURE_PARAM_PSS_SALTLEN, NULL, 0),
    OSSL_PARAM_END
};

static const OSSL_PARAM *rsa_settable_ctx_params(void *vprsactx,
                                                 ossl_unused void *provctx)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx != NULL && !prsactx->flag_allow_md)
        return settable_ctx_params_no_digest;
    return settable_ctx_params;
}

static int rsa_get_ctx_md_params(void *vprsactx, OSSL_PARAM *params)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx->mdctx == NULL)
        return 0;

    return EVP_MD_CTX_get_params(prsactx->mdctx, params);
}

static const OSSL_PARAM *rsa_gettable_ctx_md_params(void *vprsactx)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx->md == NULL)
        return 0;

    return EVP_MD_gettable_ctx_params(prsactx->md);
}

static int rsa_set_ctx_md_params(void *vprsactx, const OSSL_PARAM params[])
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx->mdctx == NULL)
        return 0;

    return EVP_MD_CTX_set_params(prsactx->mdctx, params);
}

static const OSSL_PARAM *rsa_settable_ctx_md_params(void *vprsactx)
{
    PROV_RSA_CTX *prsactx = (PROV_RSA_CTX *)vprsactx;

    if (prsactx->md == NULL)
        return 0;

    return EVP_MD_settable_ctx_params(prsactx->md);
}

const OSSL_DISPATCH ossl_rsa_signature_functions[] = {
    { OSSL_FUNC_SIGNATURE_NEWCTX, (void (*)(void))rsa_newctx },
    { OSSL_FUNC_SIGNATURE_SIGN_INIT, (void (*)(void))rsa_sign_init },
    { OSSL_FUNC_SIGNATURE_SIGN, (void (*)(void))rsa_sign },
    { OSSL_FUNC_SIGNATURE_VERIFY_INIT, (void (*)(void))rsa_verify_init },
    { OSSL_FUNC_SIGNATURE_VERIFY, (void (*)(void))rsa_verify },
    { OSSL_FUNC_SIGNATURE_VERIFY_RECOVER_INIT,
      (void (*)(void))rsa_verify_recover_init },
    { OSSL_FUNC_SIGNATURE_VERIFY_RECOVER,
      (void (*)(void))rsa_verify_recover },
    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_INIT,
      (void (*)(void))rsa_digest_sign_init },
    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_UPDATE,
      (void (*)(void))rsa_digest_signverify_update },
    { OSSL_FUNC_SIGNATURE_DIGEST_SIGN_FINAL,
      (void (*)(void))rsa_digest_sign_final },
    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_INIT,
      (void (*)(void))rsa_digest_verify_init },
    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_UPDATE,
      (void (*)(void))rsa_digest_signverify_update },
    { OSSL_FUNC_SIGNATURE_DIGEST_VERIFY_FINAL,
      (void (*)(void))rsa_digest_verify_final },
    { OSSL_FUNC_SIGNATURE_FREECTX, (void (*)(void))rsa_freectx },
    { OSSL_FUNC_SIGNATURE_DUPCTX, (void (*)(void))rsa_dupctx },
    { OSSL_FUNC_SIGNATURE_GET_CTX_PARAMS, (void (*)(void))rsa_get_ctx_params },
    { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_PARAMS,
      (void (*)(void))rsa_gettable_ctx_params },
    { OSSL_FUNC_SIGNATURE_SET_CTX_PARAMS, (void (*)(void))rsa_set_ctx_params },
    { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_PARAMS,
      (void (*)(void))rsa_settable_ctx_params },
    { OSSL_FUNC_SIGNATURE_GET_CTX_MD_PARAMS,
      (void (*)(void))rsa_get_ctx_md_params },
    { OSSL_FUNC_SIGNATURE_GETTABLE_CTX_MD_PARAMS,
      (void (*)(void))rsa_gettable_ctx_md_params },
    { OSSL_FUNC_SIGNATURE_SET_CTX_MD_PARAMS,
      (void (*)(void))rsa_set_ctx_md_params },
    { OSSL_FUNC_SIGNATURE_SETTABLE_CTX_MD_PARAMS,
      (void (*)(void))rsa_settable_ctx_md_params },
    OSSL_DISPATCH_END
};