mirror of https://github.com/openssl/openssl.git
722 lines
24 KiB
Plaintext
722 lines
24 KiB
Plaintext
=pod
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=head1 NAME
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EVP_MD_fetch, EVP_MD_up_ref, EVP_MD_free,
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EVP_MD_get_params, EVP_MD_gettable_params,
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EVP_MD_CTX_new, EVP_MD_CTX_reset, EVP_MD_CTX_free, EVP_MD_CTX_copy,
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EVP_MD_CTX_copy_ex, EVP_MD_CTX_ctrl,
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EVP_MD_CTX_set_params, EVP_MD_CTX_get_params,
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EVP_MD_settable_ctx_params, EVP_MD_gettable_ctx_params,
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EVP_MD_CTX_settable_params, EVP_MD_CTX_gettable_params,
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EVP_MD_CTX_set_flags, EVP_MD_CTX_clear_flags, EVP_MD_CTX_test_flags,
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EVP_Digest, EVP_DigestInit_ex2, EVP_DigestInit_ex, EVP_DigestInit,
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EVP_DigestUpdate, EVP_DigestFinal_ex, EVP_DigestFinalXOF, EVP_DigestFinal,
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EVP_MD_is_a, EVP_MD_name, EVP_MD_description, EVP_MD_number,
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EVP_MD_names_do_all, EVP_MD_provider,
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EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_flags,
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EVP_MD_CTX_name,
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EVP_MD_CTX_md, EVP_MD_CTX_get0_md, EVP_MD_CTX_get1_md,
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EVP_MD_CTX_type, EVP_MD_CTX_size, EVP_MD_CTX_block_size,
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EVP_MD_CTX_md_data, EVP_MD_CTX_update_fn, EVP_MD_CTX_set_update_fn,
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EVP_md_null,
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EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj,
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EVP_MD_CTX_pkey_ctx, EVP_MD_CTX_set_pkey_ctx,
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EVP_MD_do_all_provided
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- EVP digest routines
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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EVP_MD *EVP_MD_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
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const char *properties);
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int EVP_MD_up_ref(EVP_MD *md);
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void EVP_MD_free(EVP_MD *md);
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int EVP_MD_get_params(const EVP_MD *digest, OSSL_PARAM params[]);
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const OSSL_PARAM *EVP_MD_gettable_params(const EVP_MD *digest);
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EVP_MD_CTX *EVP_MD_CTX_new(void);
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int EVP_MD_CTX_reset(EVP_MD_CTX *ctx);
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void EVP_MD_CTX_free(EVP_MD_CTX *ctx);
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void EVP_MD_CTX_ctrl(EVP_MD_CTX *ctx, int cmd, int p1, void* p2);
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int EVP_MD_CTX_get_params(EVP_MD_CTX *ctx, OSSL_PARAM params[]);
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int EVP_MD_CTX_set_params(EVP_MD_CTX *ctx, const OSSL_PARAM params[]);
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const OSSL_PARAM *EVP_MD_settable_ctx_params(const EVP_MD *md);
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const OSSL_PARAM *EVP_MD_gettable_ctx_params(const EVP_MD *md);
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const OSSL_PARAM *EVP_MD_CTX_settable_params(EVP_MD_CTX *ctx);
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const OSSL_PARAM *EVP_MD_CTX_gettable_params(EVP_MD_CTX *ctx);
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void EVP_MD_CTX_set_flags(EVP_MD_CTX *ctx, int flags);
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void EVP_MD_CTX_clear_flags(EVP_MD_CTX *ctx, int flags);
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int EVP_MD_CTX_test_flags(const EVP_MD_CTX *ctx, int flags);
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int EVP_Digest(const void *data, size_t count, unsigned char *md,
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unsigned int *size, const EVP_MD *type, ENGINE *impl);
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int EVP_DigestInit_ex2(EVP_MD_CTX *ctx, const EVP_MD *type,
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const OSSL_PARAM params[]);
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int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl);
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int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt);
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int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
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int EVP_DigestFinalXOF(EVP_MD_CTX *ctx, unsigned char *md, size_t len);
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int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out, const EVP_MD_CTX *in);
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int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type);
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int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s);
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int EVP_MD_CTX_copy(EVP_MD_CTX *out, EVP_MD_CTX *in);
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const char *EVP_MD_name(const EVP_MD *md);
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const char *EVP_MD_description(const EVP_MD *md);
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int EVP_MD_number(const EVP_MD *md);
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int EVP_MD_is_a(const EVP_MD *md, const char *name);
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int EVP_MD_names_do_all(const EVP_MD *md,
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void (*fn)(const char *name, void *data),
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void *data);
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const OSSL_PROVIDER *EVP_MD_provider(const EVP_MD *md);
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int EVP_MD_type(const EVP_MD *md);
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int EVP_MD_pkey_type(const EVP_MD *md);
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int EVP_MD_size(const EVP_MD *md);
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int EVP_MD_block_size(const EVP_MD *md);
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unsigned long EVP_MD_flags(const EVP_MD *md);
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const EVP_MD *EVP_MD_CTX_get0_md(const EVP_MD_CTX *ctx);
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EVP_MD *EVP_MD_CTX_get1_md(EVP_MD_CTX *ctx);
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const char *EVP_MD_CTX_name(const EVP_MD_CTX *ctx);
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int EVP_MD_CTX_size(const EVP_MD_CTX *ctx);
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int EVP_MD_CTX_block_size(const EVP_MD_CTX *ctx);
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int EVP_MD_CTX_type(const EVP_MD_CTX *ctx);
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void *EVP_MD_CTX_md_data(const EVP_MD_CTX *ctx);
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const EVP_MD *EVP_md_null(void);
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const EVP_MD *EVP_get_digestbyname(const char *name);
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const EVP_MD *EVP_get_digestbynid(int type);
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const EVP_MD *EVP_get_digestbyobj(const ASN1_OBJECT *o);
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EVP_PKEY_CTX *EVP_MD_CTX_pkey_ctx(const EVP_MD_CTX *ctx);
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void EVP_MD_CTX_set_pkey_ctx(EVP_MD_CTX *ctx, EVP_PKEY_CTX *pctx);
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void EVP_MD_do_all_provided(OSSL_LIB_CTX *libctx,
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void (*fn)(EVP_MD *mac, void *arg),
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void *arg);
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Deprecated since OpenSSL 3.0, can be hidden entirely by defining
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B<OPENSSL_API_COMPAT> with a suitable version value, see
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L<openssl_user_macros(7)>:
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const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx);
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int (*EVP_MD_CTX_update_fn(EVP_MD_CTX *ctx))(EVP_MD_CTX *ctx,
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const void *data, size_t count);
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void EVP_MD_CTX_set_update_fn(EVP_MD_CTX *ctx,
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int (*update)(EVP_MD_CTX *ctx,
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const void *data, size_t count));
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=head1 DESCRIPTION
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The EVP digest routines are a high-level interface to message digests,
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and should be used instead of the digest-specific functions.
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The B<EVP_MD> type is a structure for digest method implementation.
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=over 4
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=item EVP_MD_fetch()
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Fetches the digest implementation for the given I<algorithm> from any
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provider offering it, within the criteria given by the I<properties>.
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See L<crypto(7)/ALGORITHM FETCHING> for further information.
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The returned value must eventually be freed with EVP_MD_free().
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Fetched B<EVP_MD> structures are reference counted.
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=item EVP_MD_up_ref()
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Increments the reference count for an B<EVP_MD> structure.
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=item EVP_MD_free()
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Decrements the reference count for the fetched B<EVP_MD> structure.
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If the reference count drops to 0 then the structure is freed.
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=item EVP_MD_CTX_new()
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Allocates and returns a digest context.
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=item EVP_MD_CTX_reset()
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Resets the digest context I<ctx>. This can be used to reuse an already
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existing context.
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=item EVP_MD_CTX_free()
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Cleans up digest context I<ctx> and frees up the space allocated to it.
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=item EVP_MD_CTX_ctrl()
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I<This is a legacy method. EVP_MD_CTX_set_params() and EVP_MD_CTX_get_params()
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is the mechanism that should be used to set and get parameters that are used by
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providers.>
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Performs digest-specific control actions on context I<ctx>. The control command
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is indicated in I<cmd> and any additional arguments in I<p1> and I<p2>.
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EVP_MD_CTX_ctrl() must be called after EVP_DigestInit_ex2(). Other restrictions
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may apply depending on the control type and digest implementation.
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If this function happens to be used with a fetched B<EVP_MD>, it will
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translate the controls that are known to OpenSSL into L<OSSL_PARAM(3)>
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parameters with keys defined by OpenSSL and call EVP_MD_CTX_get_params() or
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EVP_MD_CTX_set_params() as is appropriate for each control command.
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See L</CONTROLS> below for more information, including what translations are
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being done.
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=item EVP_MD_get_params()
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Retrieves the requested list of I<params> from a MD I<md>.
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See L</PARAMETERS> below for more information.
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=item EVP_MD_CTX_get_params()
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Retrieves the requested list of I<params> from a MD context I<ctx>.
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See L</PARAMETERS> below for more information.
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=item EVP_MD_CTX_set_params()
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Sets the list of I<params> into a MD context I<ctx>.
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See L</PARAMETERS> below for more information.
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=item EVP_MD_gettable_params()
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Get a constant B<OSSL_PARAM> array that describes the retrievable parameters
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that can be used with EVP_MD_get_params(). See L<OSSL_PARAM(3)> for the
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use of B<OSSL_PARAM> as a parameter descriptor.
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=item EVP_MD_gettable_ctx_params(), EVP_MD_CTX_gettable_params()
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Get a constant B<OSSL_PARAM> array that describes the retrievable parameters
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that can be used with EVP_MD_CTX_get_params(). EVP_MD_gettable_ctx_params()
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returns the parameters that can be retrieved from the algorithm, whereas
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EVP_MD_CTX_gettable_params() returns the parameters that can be retrieved
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in the context's current state. See L<OSSL_PARAM(3)> for the use of
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B<OSSL_PARAM> as a parameter descriptor.
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=item EVP_MD_settable_ctx_params(), EVP_MD_CTX_settable_params()
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Get a constant B<OSSL_PARAM> array that describes the settable parameters
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that can be used with EVP_MD_CTX_set_params(). EVP_MD_settable_ctx_params()
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returns the parameters that can be set from the algorithm, whereas
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EVP_MD_CTX_settable_params() returns the parameters that can be set in the
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context's current state. See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM>
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as a parameter descriptor.
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=item EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags(), EVP_MD_CTX_test_flags()
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Sets, clears and tests I<ctx> flags. See L</FLAGS> below for more information.
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=item EVP_Digest()
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A wrapper around the Digest Init_ex, Update and Final_ex functions.
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Hashes I<count> bytes of data at I<data> using a digest I<type> from ENGINE
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I<impl>. The digest value is placed in I<md> and its length is written at I<size>
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if the pointer is not NULL. At most B<EVP_MAX_MD_SIZE> bytes will be written.
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If I<impl> is NULL the default implementation of digest I<type> is used.
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=item EVP_DigestInit_ex2()
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Sets up digest context I<ctx> to use a digest I<type>.
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I<type> is typically supplied by a function such as EVP_sha1(), or a
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value explicitly fetched with EVP_MD_fetch().
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The parameters B<params> are set on the context after initialisation.
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The I<type> parameter can be NULL if I<ctx> has been already initialized
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with another EVP_DigestInit_ex() call and has not been reset with
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EVP_MD_CTX_reset().
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=item EVP_DigestInit_ex()
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Sets up digest context I<ctx> to use a digest I<type>.
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I<type> is typically supplied by a function such as EVP_sha1(), or a
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value explicitly fetched with EVP_MD_fetch().
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If I<impl> is non-NULL, its implementation of the digest I<type> is used if
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there is one, and if not, the default implementation is used.
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The I<type> parameter can be NULL if I<ctx> has been already initialized
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with another EVP_DigestInit_ex() call and has not been reset with
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EVP_MD_CTX_reset().
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=item EVP_DigestUpdate()
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Hashes I<cnt> bytes of data at I<d> into the digest context I<ctx>. This
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function can be called several times on the same I<ctx> to hash additional
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data.
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=item EVP_DigestFinal_ex()
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Retrieves the digest value from I<ctx> and places it in I<md>. If the I<s>
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parameter is not NULL then the number of bytes of data written (i.e. the
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length of the digest) will be written to the integer at I<s>, at most
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B<EVP_MAX_MD_SIZE> bytes will be written. After calling EVP_DigestFinal_ex()
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no additional calls to EVP_DigestUpdate() can be made, but
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EVP_DigestInit_ex2() can be called to initialize a new digest operation.
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=item EVP_DigestFinalXOF()
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Interfaces to extendable-output functions, XOFs, such as SHAKE128 and SHAKE256.
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It retrieves the digest value from I<ctx> and places it in I<len>-sized I<md>.
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After calling this function no additional calls to EVP_DigestUpdate() can be
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made, but EVP_DigestInit_ex2() can be called to initialize a new operation.
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=item EVP_MD_CTX_copy_ex()
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Can be used to copy the message digest state from I<in> to I<out>. This is
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useful if large amounts of data are to be hashed which only differ in the last
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few bytes.
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=item EVP_DigestInit()
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Behaves in the same way as EVP_DigestInit_ex2() except it doesn't set any
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parameters and calls EVP_MD_CTX_reset() so it cannot be used with an I<type>
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of NULL.
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=item EVP_DigestFinal()
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Similar to EVP_DigestFinal_ex() except after computing the digest
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the digest context I<ctx> is automatically cleaned up with EVP_MD_CTX_reset().
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=item EVP_MD_CTX_copy()
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Similar to EVP_MD_CTX_copy_ex() except the destination I<out> does not have to
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be initialized.
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=item EVP_MD_is_a()
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Returns 1 if I<md> is an implementation of an algorithm that's
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identifiable with I<name>, otherwise 0.
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If I<md> is a legacy digest (it's the return value from the likes of
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EVP_sha256() rather than the result of an EVP_MD_fetch()), only cipher
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names registered with the default library context (see
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L<OSSL_LIB_CTX(3)>) will be considered.
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=item EVP_MD_number()
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Returns the internal dynamic number assigned to the I<md>. This is
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only useful with fetched B<EVP_MD>s.
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=item EVP_MD_name(),
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EVP_MD_CTX_name()
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Return the name of the given message digest. For fetched message
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digests with multiple names, only one of them is returned; it's
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recommended to use EVP_MD_names_do_all() instead.
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=item EVP_MD_names_do_all()
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Traverses all names for the I<md>, and calls I<fn> with each name and
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I<data>. This is only useful with fetched B<EVP_MD>s.
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=item EVP_MD_description()
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Returns a description of the digest, meant for display and human consumption.
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The description is at the discretion of the digest implementation.
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=item EVP_MD_provider()
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Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given
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B<EVP_MD>.
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=item EVP_MD_size(),
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EVP_MD_CTX_size()
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Return the size of the message digest when passed an B<EVP_MD> or an
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B<EVP_MD_CTX> structure, i.e. the size of the hash.
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=item EVP_MD_block_size(),
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EVP_MD_CTX_block_size()
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Return the block size of the message digest when passed an B<EVP_MD> or an
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B<EVP_MD_CTX> structure.
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=item EVP_MD_type(),
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EVP_MD_CTX_type()
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Return the NID of the OBJECT IDENTIFIER representing the given message digest
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when passed an B<EVP_MD> structure. For example, C<EVP_MD_type(EVP_sha1())>
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returns B<NID_sha1>. This function is normally used when setting ASN1 OIDs.
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=item EVP_MD_CTX_md_data()
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Return the digest method private data for the passed B<EVP_MD_CTX>.
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The space is allocated by OpenSSL and has the size originally set with
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EVP_MD_meth_set_app_datasize().
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=item EVP_MD_CTX_get0_md(), EVP_MD_CTX_get1_md()
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EVP_MD_CTX_get0_md() returns
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the B<EVP_MD> structure corresponding to the passed B<EVP_MD_CTX>. This
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will be the same B<EVP_MD> object originally passed to EVP_DigestInit_ex2() (or
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other similar function) when the EVP_MD_CTX was first initialised. Note that
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where explicit fetch is in use (see L<EVP_MD_fetch(3)>) the value returned from
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this function will not have its reference count incremented and therefore it
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should not be used after the EVP_MD_CTX is freed.
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EVP_MD_CTX_get1_md() is the same except the ownership is passed to the
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caller and is from the passed B<EVP_MD_CTX>.
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=item EVP_MD_CTX_set_update_fn()
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Sets the update function for I<ctx> to I<update>.
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This is the function that is called by EVP_DigestUpdate(). If not set, the
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update function from the B<EVP_MD> type specified at initialization is used.
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=item EVP_MD_CTX_update_fn()
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Returns the update function for I<ctx>.
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=item EVP_MD_flags()
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Returns the I<md> flags. Note that these are different from the B<EVP_MD_CTX>
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ones. See L<EVP_MD_meth_set_flags(3)> for more information.
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=item EVP_MD_pkey_type()
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Returns the NID of the public key signing algorithm associated with this
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digest. For example EVP_sha1() is associated with RSA so this will return
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B<NID_sha1WithRSAEncryption>. Since digests and signature algorithms are no
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longer linked this function is only retained for compatibility reasons.
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=item EVP_md_null()
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A "null" message digest that does nothing: i.e. the hash it returns is of zero
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length.
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=item EVP_get_digestbyname(),
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EVP_get_digestbynid(),
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EVP_get_digestbyobj()
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Returns an B<EVP_MD> structure when passed a digest name, a digest B<NID> or an
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B<ASN1_OBJECT> structure respectively.
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=item EVP_MD_CTX_pkey_ctx()
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Returns the B<EVP_PKEY_CTX> assigned to I<ctx>. The returned pointer should not
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be freed by the caller.
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=item EVP_MD_CTX_set_pkey_ctx()
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Assigns an B<EVP_PKEY_CTX> to B<EVP_MD_CTX>. This is usually used to provide
|
|
a customized B<EVP_PKEY_CTX> to L<EVP_DigestSignInit(3)> or
|
|
L<EVP_DigestVerifyInit(3)>. The I<pctx> passed to this function should be freed
|
|
by the caller. A NULL I<pctx> pointer is also allowed to clear the B<EVP_PKEY_CTX>
|
|
assigned to I<ctx>. In such case, freeing the cleared B<EVP_PKEY_CTX> or not
|
|
depends on how the B<EVP_PKEY_CTX> is created.
|
|
|
|
=item EVP_MD_do_all_provided()
|
|
|
|
Traverses all messages digests implemented by all activated providers
|
|
in the given library context I<libctx>, and for each of the implementations,
|
|
calls the given function I<fn> with the implementation method and the given
|
|
I<arg> as argument.
|
|
|
|
=back
|
|
|
|
=head1 PARAMETERS
|
|
|
|
See L<OSSL_PARAM(3)> for information about passing parameters.
|
|
|
|
EVP_MD_CTX_set_params() can be used with the following OSSL_PARAM keys:
|
|
|
|
=over 4
|
|
|
|
=item "xoflen" (B<OSSL_DIGEST_PARAM_XOFLEN>) <unsigned integer>
|
|
|
|
Sets the digest length for extendable output functions.
|
|
It is used by the SHAKE algorithm and should not exceed what can be given
|
|
using a B<size_t>.
|
|
|
|
=item "pad-type" (B<OSSL_DIGEST_PARAM_PAD_TYPE>) <unsigned integer>
|
|
|
|
Sets the padding type.
|
|
It is used by the MDC2 algorithm.
|
|
|
|
=back
|
|
|
|
EVP_MD_CTX_get_params() can be used with the following OSSL_PARAM keys:
|
|
|
|
=over 4
|
|
|
|
=item "micalg" (B<OSSL_PARAM_DIGEST_KEY_MICALG>) <UTF8 string>.
|
|
|
|
Gets the digest Message Integrity Check algorithm string. This is used when
|
|
creating S/MIME multipart/signed messages, as specified in RFC 3851.
|
|
It may be used by external engines or providers.
|
|
|
|
=back
|
|
|
|
=head1 CONTROLS
|
|
|
|
EVP_MD_CTX_ctrl() can be used to send the following standard controls:
|
|
|
|
=over 4
|
|
|
|
=item EVP_MD_CTRL_MICALG
|
|
|
|
Gets the digest Message Integrity Check algorithm string. This is used when
|
|
creating S/MIME multipart/signed messages, as specified in RFC 3851.
|
|
The string value is written to I<p2>.
|
|
|
|
When used with a fetched B<EVP_MD>, EVP_MD_CTX_get_params() gets called with
|
|
an L<OSSL_PARAM(3)> item with the key "micalg" (B<OSSL_DIGEST_PARAM_MICALG>).
|
|
|
|
=item EVP_MD_CTRL_XOF_LEN
|
|
|
|
This control sets the digest length for extendable output functions to I<p1>.
|
|
Sending this control directly should not be necessary, the use of
|
|
EVP_DigestFinalXOF() is preferred.
|
|
Currently used by SHAKE.
|
|
|
|
When used with a fetched B<EVP_MD>, EVP_MD_CTX_get_params() gets called with
|
|
an L<OSSL_PARAM(3)> item with the key "xoflen" (B<OSSL_DIGEST_PARAM_XOFLEN>).
|
|
|
|
=back
|
|
|
|
=head1 FLAGS
|
|
|
|
EVP_MD_CTX_set_flags(), EVP_MD_CTX_clear_flags() and EVP_MD_CTX_test_flags()
|
|
can be used the manipulate and test these B<EVP_MD_CTX> flags:
|
|
|
|
=over 4
|
|
|
|
=item EVP_MD_CTX_FLAG_ONESHOT
|
|
|
|
This flag instructs the digest to optimize for one update only, if possible.
|
|
|
|
=for comment EVP_MD_CTX_FLAG_CLEANED is internal, don't mention it
|
|
|
|
=for comment EVP_MD_CTX_FLAG_REUSE is internal, don't mention it
|
|
|
|
=for comment We currently avoid documenting flags that are only bit holder:
|
|
EVP_MD_CTX_FLAG_NON_FIPS_ALLOW, EVP_MD_CTX_FLAGS_PAD_*
|
|
|
|
=item EVP_MD_CTX_FLAG_NO_INIT
|
|
|
|
This flag instructs EVP_DigestInit() and similar not to initialise the
|
|
implementation specific data.
|
|
|
|
=item EVP_MD_CTX_FLAG_FINALISE
|
|
|
|
Some functions such as EVP_DigestSign only finalise copies of internal
|
|
contexts so additional data can be included after the finalisation call.
|
|
This is inefficient if this functionality is not required, and can be
|
|
disabled with this flag.
|
|
|
|
=back
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
=over 4
|
|
|
|
=item EVP_MD_fetch()
|
|
|
|
Returns a pointer to a B<EVP_MD> for success or NULL for failure.
|
|
|
|
=item EVP_MD_up_ref()
|
|
|
|
Returns 1 for success or 0 for failure.
|
|
|
|
=item EVP_DigestInit_ex2(),
|
|
EVP_DigestInit_ex(),
|
|
EVP_DigestUpdate(),
|
|
EVP_DigestFinal_ex()
|
|
|
|
Returns 1 for
|
|
success and 0 for failure.
|
|
|
|
=item EVP_MD_CTX_ctrl()
|
|
|
|
Returns 1 if successful or 0 for failure.
|
|
|
|
=item EVP_MD_CTX_set_params(),
|
|
EVP_MD_CTX_get_params()
|
|
|
|
Returns 1 if successful or 0 for failure.
|
|
|
|
=item EVP_MD_CTX_settable_params(),
|
|
EVP_MD_CTX_gettable_params()
|
|
|
|
Return an array of constant B<OSSL_PARAM>s, or NULL if there is none
|
|
to get.
|
|
|
|
=item EVP_MD_CTX_copy_ex()
|
|
|
|
Returns 1 if successful or 0 for failure.
|
|
|
|
=item EVP_MD_type(),
|
|
EVP_MD_pkey_type()
|
|
|
|
Returns the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none
|
|
exists.
|
|
|
|
=item EVP_MD_size(),
|
|
EVP_MD_block_size(),
|
|
EVP_MD_CTX_size(),
|
|
EVP_MD_CTX_block_size()
|
|
|
|
Returns the digest or block size in bytes.
|
|
|
|
=item EVP_md_null()
|
|
|
|
Returns a pointer to the B<EVP_MD> structure of the "null" message digest.
|
|
|
|
=item EVP_get_digestbyname(),
|
|
EVP_get_digestbynid(),
|
|
EVP_get_digestbyobj()
|
|
|
|
Returns either an B<EVP_MD> structure or NULL if an error occurs.
|
|
|
|
=item EVP_MD_CTX_set_pkey_ctx()
|
|
|
|
This function has no return value.
|
|
|
|
=item EVP_MD_names_do_all()
|
|
|
|
Returns 1 if the callback was called for all names. A return value of 0 means
|
|
that the callback was not called for any names.
|
|
|
|
=back
|
|
|
|
=head1 NOTES
|
|
|
|
The B<EVP> interface to message digests should almost always be used in
|
|
preference to the low-level interfaces. This is because the code then becomes
|
|
transparent to the digest used and much more flexible.
|
|
|
|
New applications should use the SHA-2 (such as L<EVP_sha256(3)>) or the SHA-3
|
|
digest algorithms (such as L<EVP_sha3_512(3)>). The other digest algorithms
|
|
are still in common use.
|
|
|
|
For most applications the I<impl> parameter to EVP_DigestInit_ex() will be
|
|
set to NULL to use the default digest implementation.
|
|
|
|
The functions EVP_DigestInit(), EVP_DigestFinal() and EVP_MD_CTX_copy() are
|
|
obsolete but are retained to maintain compatibility with existing code. New
|
|
applications should use EVP_DigestInit_ex(), EVP_DigestFinal_ex() and
|
|
EVP_MD_CTX_copy_ex() because they can efficiently reuse a digest context
|
|
instead of initializing and cleaning it up on each call and allow non default
|
|
implementations of digests to be specified.
|
|
|
|
If digest contexts are not cleaned up after use,
|
|
memory leaks will occur.
|
|
|
|
EVP_MD_CTX_name(), EVP_MD_CTX_size(), EVP_MD_CTX_block_size(),
|
|
EVP_MD_CTX_type(), EVP_get_digestbynid() and EVP_get_digestbyobj() are defined
|
|
as macros.
|
|
|
|
EVP_MD_CTX_ctrl() sends commands to message digests for additional configuration
|
|
or control.
|
|
|
|
=head1 EXAMPLES
|
|
|
|
This example digests the data "Test Message\n" and "Hello World\n", using the
|
|
digest name passed on the command line.
|
|
|
|
#include <stdio.h>
|
|
#include <string.h>
|
|
#include <openssl/evp.h>
|
|
|
|
int main(int argc, char *argv[])
|
|
{
|
|
EVP_MD_CTX *mdctx;
|
|
const EVP_MD *md;
|
|
char mess1[] = "Test Message\n";
|
|
char mess2[] = "Hello World\n";
|
|
unsigned char md_value[EVP_MAX_MD_SIZE];
|
|
unsigned int md_len, i;
|
|
|
|
if (argv[1] == NULL) {
|
|
printf("Usage: mdtest digestname\n");
|
|
exit(1);
|
|
}
|
|
|
|
md = EVP_get_digestbyname(argv[1]);
|
|
if (md == NULL) {
|
|
printf("Unknown message digest %s\n", argv[1]);
|
|
exit(1);
|
|
}
|
|
|
|
mdctx = EVP_MD_CTX_new();
|
|
EVP_DigestInit_ex2(mdctx, md, NULL);
|
|
EVP_DigestUpdate(mdctx, mess1, strlen(mess1));
|
|
EVP_DigestUpdate(mdctx, mess2, strlen(mess2));
|
|
EVP_DigestFinal_ex(mdctx, md_value, &md_len);
|
|
EVP_MD_CTX_free(mdctx);
|
|
|
|
printf("Digest is: ");
|
|
for (i = 0; i < md_len; i++)
|
|
printf("%02x", md_value[i]);
|
|
printf("\n");
|
|
|
|
exit(0);
|
|
}
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<EVP_MD_meth_new(3)>,
|
|
L<openssl-dgst(1)>,
|
|
L<evp(7)>,
|
|
L<OSSL_PROVIDER(3)>,
|
|
L<OSSL_PARAM(3)>
|
|
|
|
The full list of digest algorithms are provided below.
|
|
|
|
L<EVP_blake2b512(3)>,
|
|
L<EVP_md2(3)>,
|
|
L<EVP_md4(3)>,
|
|
L<EVP_md5(3)>,
|
|
L<EVP_mdc2(3)>,
|
|
L<EVP_ripemd160(3)>,
|
|
L<EVP_sha1(3)>,
|
|
L<EVP_sha224(3)>,
|
|
L<EVP_sha3_224(3)>,
|
|
L<EVP_sm3(3)>,
|
|
L<EVP_whirlpool(3)>
|
|
L<crypto(7)/ALGORITHM FETCHING>
|
|
|
|
=head1 HISTORY
|
|
|
|
The EVP_MD_CTX_create() and EVP_MD_CTX_destroy() functions were renamed to
|
|
EVP_MD_CTX_new() and EVP_MD_CTX_free() in OpenSSL 1.1.0, respectively.
|
|
|
|
The link between digests and signing algorithms was fixed in OpenSSL 1.0 and
|
|
later, so now EVP_sha1() can be used with RSA and DSA.
|
|
|
|
The EVP_dss1() function was removed in OpenSSL 1.1.0.
|
|
|
|
The EVP_MD_CTX_set_pkey_ctx() function was added in OpenSSL 1.1.1.
|
|
|
|
The EVP_DigestInit_ex2(), EVP_MD_fetch(), EVP_MD_free(), EVP_MD_up_ref(),
|
|
EVP_MD_get_params(), EVP_MD_CTX_set_params(), EVP_MD_CTX_get_params(),
|
|
EVP_MD_gettable_params(), EVP_MD_gettable_ctx_params(),
|
|
EVP_MD_settable_ctx_params(), EVP_MD_CTX_settable_params() and
|
|
EVP_MD_CTX_gettable_params() functions were added in OpenSSL 3.0.
|
|
|
|
The EVP_MD_CTX_md() function was deprecated in OpenSSL 3.0; use
|
|
EVP_MD_CTX_get0_md() instead.
|
|
EVP_MD_CTX_update_fn() and EVP_MD_CTX_set_update_fn() were deprecated
|
|
in OpenSSL 3.0.
|
|
|
|
=head1 COPYRIGHT
|
|
|
|
Copyright 2000-2021 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
|
|
L<https://www.openssl.org/source/license.html>.
|
|
|
|
=cut
|