EVP_DigestInit(3) OpenSSL EVP_DigestInit(3) NNAAMMEE EVP_MD_CTX_init, EVP_MD_CTX_create, EVP_DigestInit_ex, EVP_DigestUp- date, EVP_DigestFinal_ex, EVP_MD_CTX_cleanup, EVP_MD_CTX_destroy, EVP_MAX_MD_SIZE, EVP_MD_CTX_copy_ex, EVP_MD_CTX_copy, EVP_MD_type, EVP_MD_pkey_type, EVP_MD_size, EVP_MD_block_size, EVP_MD_CTX_md, EVP_MD_CTX_size, EVP_MD_CTX_block_size, EVP_MD_CTX_type, EVP_md_null, EVP_md2, EVP_md5, EVP_sha, EVP_sha1, EVP_sha224, EVP_sha256, EVP_sha384, EVP_sha512, EVP_dss, EVP_dss1, EVP_mdc2, EVP_ripemd160, EVP_get_digestbyname, EVP_get_digestbynid, EVP_get_digestbyobj - EVP digest routines SSYYNNOOPPSSIISS #include void EVP_MD_CTX_init(EVP_MD_CTX *ctx); EVP_MD_CTX *EVP_MD_CTX_create(void); int EVP_DigestInit_ex(EVP_MD_CTX *ctx, const EVP_MD *type, ENGINE *impl); int EVP_DigestUpdate(EVP_MD_CTX *ctx, const void *d, size_t cnt); int EVP_DigestFinal_ex(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s); int EVP_MD_CTX_cleanup(EVP_MD_CTX *ctx); void EVP_MD_CTX_destroy(EVP_MD_CTX *ctx); int EVP_MD_CTX_copy_ex(EVP_MD_CTX *out,const EVP_MD_CTX *in); int EVP_DigestInit(EVP_MD_CTX *ctx, const EVP_MD *type); int EVP_DigestFinal(EVP_MD_CTX *ctx, unsigned char *md, unsigned int *s); int EVP_MD_CTX_copy(EVP_MD_CTX *out,EVP_MD_CTX *in); #define EVP_MAX_MD_SIZE 64 /* SHA512 */ int EVP_MD_type(const EVP_MD *md); int EVP_MD_pkey_type(const EVP_MD *md); int EVP_MD_size(const EVP_MD *md); int EVP_MD_block_size(const EVP_MD *md); const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *ctx); #define EVP_MD_CTX_size(e) EVP_MD_size(EVP_MD_CTX_md(e)) #define EVP_MD_CTX_block_size(e) EVP_MD_block_size((e)->digest) #define EVP_MD_CTX_type(e) EVP_MD_type((e)->digest) const EVP_MD *EVP_md_null(void); const EVP_MD *EVP_md2(void); const EVP_MD *EVP_md5(void); const EVP_MD *EVP_sha(void); const EVP_MD *EVP_sha1(void); const EVP_MD *EVP_dss(void); const EVP_MD *EVP_dss1(void); const EVP_MD *EVP_mdc2(void); const EVP_MD *EVP_ripemd160(void); const EVP_MD *EVP_sha224(void); const EVP_MD *EVP_sha256(void); const EVP_MD *EVP_sha384(void); const EVP_MD *EVP_sha512(void); const EVP_MD *EVP_get_digestbyname(const char *name); #define EVP_get_digestbynid(a) EVP_get_digestbyname(OBJ_nid2sn(a)) #define EVP_get_digestbyobj(a) EVP_get_digestbynid(OBJ_obj2nid(a)) DDEESSCCRRIIPPTTIIOONN The EVP digest routines are a high level interface to message digests. _E_V_P___M_D___C_T_X___i_n_i_t_(_) initializes digest context ccttxx. _E_V_P___M_D___C_T_X___c_r_e_a_t_e_(_) allocates, initializes and returns a digest con- text. _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_) sets up digest context ccttxx to use a digest ttyyppee from ENGINE iimmppll. ccttxx must be initialized before calling this function. ttyyppee will typically be supplied by a functionsuch as _E_V_P___s_h_a_1_(_). If iimmppll is NULL then the default implementation of digest ttyyppee is used. _E_V_P___D_i_g_e_s_t_U_p_d_a_t_e_(_) hashes ccnntt bytes of data at dd into the digest con- text ccttxx. This function can be called several times on the same ccttxx to hash additional data. _E_V_P___D_i_g_e_s_t_F_i_n_a_l___e_x_(_) retrieves the digest value from ccttxx and places it in mmdd. If the ss parameter is not NULL then the number of bytes of data written (i.e. the length of the digest) will be written to the integer at ss, at most EEVVPP__MMAAXX__MMDD__SSIIZZEE bytes will be written. After calling _E_V_P___D_i_g_e_s_t_F_i_n_a_l___e_x_(_) no additional calls to _E_V_P___D_i_g_e_s_t_U_p_d_a_t_e_(_) can be made, but _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_) can be called to initialize a new digest operation. _E_V_P___M_D___C_T_X___c_l_e_a_n_u_p_(_) cleans up digest context ccttxx, it should be called after a digest context is no longer needed. _E_V_P___M_D___C_T_X___d_e_s_t_r_o_y_(_) cleans up digest context ccttxx and frees up the space allocated to it, it should be called only on a context created using _E_V_P___M_D___C_T_X___c_r_e_a_t_e_(_). _E_V_P___M_D___C_T_X___c_o_p_y___e_x_(_) can be used to copy the message digest state from iinn to oouutt. This is useful if large amounts of data are to be hashed which only differ in the last few bytes. oouutt must be initialized before calling this function. _E_V_P___D_i_g_e_s_t_I_n_i_t_(_) behaves in the same way as _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_) except the passed context ccttxx does not have to be initialized, and it always uses the default digest implementation. _E_V_P___D_i_g_e_s_t_F_i_n_a_l_(_) is similar to _E_V_P___D_i_g_e_s_t_F_i_n_a_l___e_x_(_) except the digest context ccttxx is automatically cleaned up. _E_V_P___M_D___C_T_X___c_o_p_y_(_) is similar to _E_V_P___M_D___C_T_X___c_o_p_y___e_x_(_) except the desti- nation oouutt does not have to be initialized. _E_V_P___M_D___s_i_z_e_(_) and _E_V_P___M_D___C_T_X___s_i_z_e_(_) return the size of the message digest when passed an EEVVPP__MMDD or an EEVVPP__MMDD__CCTTXX structure, i.e. the size of the hash. _E_V_P___M_D___b_l_o_c_k___s_i_z_e_(_) and _E_V_P___M_D___C_T_X___b_l_o_c_k___s_i_z_e_(_) return the block size of the message digest when passed an EEVVPP__MMDD or an EEVVPP__MMDD__CCTTXX structure. _E_V_P___M_D___t_y_p_e_(_) and _E_V_P___M_D___C_T_X___t_y_p_e_(_) return the NID of the OBJECT IDEN- TIFIER representing the given message digest when passed an EEVVPP__MMDD structure. For example EVP_MD_type(_E_V_P___s_h_a_1_(_)) returns NNIIDD__sshhaa11. This function is normally used when setting ASN1 OIDs. _E_V_P___M_D___C_T_X___m_d_(_) returns the EEVVPP__MMDD structure corresponding to the passed EEVVPP__MMDD__CCTTXX. _E_V_P___M_D___p_k_e_y___t_y_p_e_(_) returns the NID of the public key signing algorithm associated with this digest. For example _E_V_P___s_h_a_1_(_) is associated with RSA so this will return NNIIDD__sshhaa11WWiitthhRRSSAAEEnnccrryyppttiioonn. Since digests and signature algorithms are no longer linked this function is only retained for compatibility reasons. _E_V_P___m_d_2_(_), _E_V_P___m_d_5_(_), _E_V_P___s_h_a_(_), _E_V_P___s_h_a_1_(_), _E_V_P___s_h_a_2_2_4_(_), _E_V_P___s_h_a_2_5_6_(_), _E_V_P___s_h_a_3_8_4_(_), _E_V_P___s_h_a_5_1_2_(_), _E_V_P___m_d_c_2_(_) and _E_V_P___r_i_p_e_m_d_1_6_0_(_) return EEVVPP__MMDD structures for the MD2, MD5, SHA, SHA1, SHA224, SHA256, SHA384, SHA512, MDC2 and RIPEMD160 digest algorithms respectively. _E_V_P___d_s_s_(_) and _E_V_P___d_s_s_1_(_) return EEVVPP__MMDD structures for SHA and SHA1 digest algorithms but using DSS (DSA) for the signature algorithm. Note: there is no need to use these pseudo-digests in OpenSSL 1.0.0 and later, they are however retained for compatibility. _E_V_P___m_d___n_u_l_l_(_) is a "null" message digest that does nothing: i.e. the hash it returns is of zero length. _E_V_P___g_e_t___d_i_g_e_s_t_b_y_n_a_m_e_(_), _E_V_P___g_e_t___d_i_g_e_s_t_b_y_n_i_d_(_) and _E_V_P___g_e_t___d_i_g_e_s_t_b_y_o_b_j_(_) return an EEVVPP__MMDD structure when passed a digest name, a digest NID or an ASN1_OBJECT structure respectively. The digest table must be ini- tialized using, for example, _O_p_e_n_S_S_L___a_d_d___a_l_l___d_i_g_e_s_t_s_(_) for these func- tions to work. RREETTUURRNN VVAALLUUEESS _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_), _E_V_P___D_i_g_e_s_t_U_p_d_a_t_e_(_) and _E_V_P___D_i_g_e_s_t_F_i_n_a_l___e_x_(_) return 1 for success and 0 for failure. _E_V_P___M_D___C_T_X___c_o_p_y___e_x_(_) returns 1 if successful or 0 for failure. _E_V_P___M_D___t_y_p_e_(_), _E_V_P___M_D___p_k_e_y___t_y_p_e_(_) and _E_V_P___M_D___t_y_p_e_(_) return the NID of the corresponding OBJECT IDENTIFIER or NID_undef if none exists. _E_V_P___M_D___s_i_z_e_(_), _E_V_P___M_D___b_l_o_c_k___s_i_z_e_(_), _E_V_P___M_D___C_T_X___s_i_z_e_(_) and _E_V_P___M_D___C_T_X___b_l_o_c_k___s_i_z_e_(_) return the digest or block size in bytes. _E_V_P___m_d___n_u_l_l_(_), _E_V_P___m_d_2_(_), _E_V_P___m_d_5_(_), _E_V_P___s_h_a_(_), _E_V_P___s_h_a_1_(_), _E_V_P___d_s_s_(_), _E_V_P___d_s_s_1_(_), _E_V_P___m_d_c_2_(_) and _E_V_P___r_i_p_e_m_d_1_6_0_(_) return pointers to the cor- responding EVP_MD structures. _E_V_P___g_e_t___d_i_g_e_s_t_b_y_n_a_m_e_(_), _E_V_P___g_e_t___d_i_g_e_s_t_b_y_n_i_d_(_) and _E_V_P___g_e_t___d_i_g_e_s_t_b_y_o_b_j_(_) return either an EEVVPP__MMDD structure or NULL if an error occurs. NNOOTTEESS The EEVVPP 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 SHA2 digest algorithms such as SHA256. The other digest algorithms are still in common use. For most applications the iimmppll parameter to _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_) will be set to NULL to use the default digest implementation. The functions _E_V_P___D_i_g_e_s_t_I_n_i_t_(_), _E_V_P___D_i_g_e_s_t_F_i_n_a_l_(_) and _E_V_P___M_D___C_T_X___c_o_p_y_(_) are obsolete but are retained to maintain compatibility with existing code. New applications should use _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_), _E_V_P___D_i_g_e_s_t_F_i_- _n_a_l___e_x_(_) and _E_V_P___M_D___C_T_X___c_o_p_y___e_x_(_) 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. In OpenSSL 0.9.7 and later if digest contexts are not cleaned up after use memory leaks will occur. Stack allocation of EVP_MD_CTX structures is common, for example: EVP_MD_CTX mctx; EVP_MD_CTX_init(&mctx); This will cause binary compatibility issues if the size of EVP_MD_CTX structure changes (this will only happen with a major release of OpenSSL). Applications wishing to avoid this should use _E_V_P___M_D___C_T_X___c_r_e_a_t_e_(_) instead: EVP_MD_CTX *mctx; mctx = EVP_MD_CTX_create(); EEXXAAMMPPLLEE This example digests the data "Test Message\n" and "Hello World\n", using the digest name passed on the command line. #include #include 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]; int md_len, i; OpenSSL_add_all_digests(); if(!argv[1]) { printf("Usage: mdtest digestname\n"); exit(1); } md = EVP_get_digestbyname(argv[1]); if(!md) { printf("Unknown message digest %s\n", argv[1]); exit(1); } mdctx = EVP_MD_CTX_create(); EVP_DigestInit_ex(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_destroy(mdctx); printf("Digest is: "); for(i = 0; i < md_len; i++) printf("%02x", md_value[i]); printf("\n"); /* Call this once before exit. */ EVP_cleanup(); exit(0); } SSEEEE AALLSSOO _d_g_s_t(1), _e_v_p(3) HHIISSTTOORRYY _E_V_P___D_i_g_e_s_t_I_n_i_t_(_), _E_V_P___D_i_g_e_s_t_U_p_d_a_t_e_(_) and _E_V_P___D_i_g_e_s_t_F_i_n_a_l_(_) are avail- able in all versions of SSLeay and OpenSSL. _E_V_P___M_D___C_T_X___i_n_i_t_(_), _E_V_P___M_D___C_T_X___c_r_e_a_t_e_(_), _E_V_P___M_D___C_T_X___c_o_p_y___e_x_(_), _E_V_P___M_D___C_T_X___c_l_e_a_n_u_p_(_), _E_V_P___M_D___C_T_X___d_e_s_t_r_o_y_(_), _E_V_P___D_i_g_e_s_t_I_n_i_t___e_x_(_) and _E_V_P___D_i_g_e_s_t_F_i_n_a_l___e_x_(_) were added in OpenSSL 0.9.7. _E_V_P___m_d___n_u_l_l_(_), _E_V_P___m_d_2_(_), _E_V_P___m_d_5_(_), _E_V_P___s_h_a_(_), _E_V_P___s_h_a_1_(_), _E_V_P___d_s_s_(_), _E_V_P___d_s_s_1_(_), _E_V_P___m_d_c_2_(_) and _E_V_P___r_i_p_e_m_d_1_6_0_(_) were changed to return tru- ely const EVP_MD * in OpenSSL 0.9.7. The link between digests and signing algorithms was fixed in OpenSSL 1.0 and later, so now _E_V_P___s_h_a_1_(_) can be used with RSA and DSA; there is no need to use _E_V_P___d_s_s_1_(_) any more. OpenSSL 1.0 and later does not include the MD2 digest algorithm in the default configuration due to its security weaknesses. 1.0.1u 2016-09-22 EVP_DigestInit(3)