| EVP_EncryptInit.pod (59191) | EVP_EncryptInit.pod (68651) |
|---|---|
| 1=pod 2 3=head1 NAME 4 | 1=pod 2 3=head1 NAME 4 |
| 5EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal - EVP cipher routines | 5EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal, EVP_DecryptInit, 6EVP_DecryptUpdate, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherUpdate, 7EVP_CipherFinal, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl, 8EVP_CIPHER_CTX_cleanup, EVP_get_cipherbyname, EVP_get_cipherbynid, 9EVP_get_cipherbyobj, EVP_CIPHER_nid, EVP_CIPHER_block_size, 10EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags, 11EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid, 12EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length, 13EVP_CIPHER_CTX_get_app_data, EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, 14EVP_CIPHER_CTX_flags, EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, 15EVP_CIPHER_asn1_to_param - EVP cipher routines |
| 6 7=head1 SYNOPSIS 8 9 #include <openssl/evp.h> 10 | 16 17=head1 SYNOPSIS 18 19 #include <openssl/evp.h> 20 |
| 11 void EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, | 21 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, |
| 12 unsigned char *key, unsigned char *iv); | 22 unsigned char *key, unsigned char *iv); |
| 13 void EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, | 23 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, |
| 14 int *outl, unsigned char *in, int inl); | 24 int *outl, unsigned char *in, int inl); |
| 15 void EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, | 25 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, |
| 16 int *outl); 17 | 26 int *outl); 27 |
| 18 void EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, | 28 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, |
| 19 unsigned char *key, unsigned char *iv); | 29 unsigned char *key, unsigned char *iv); |
| 20 void EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, | 30 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, |
| 21 int *outl, unsigned char *in, int inl); 22 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, 23 int *outl); 24 | 31 int *outl, unsigned char *in, int inl); 32 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, 33 int *outl); 34 |
| 25 void EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, | 35 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, |
| 26 unsigned char *key, unsigned char *iv, int enc); | 36 unsigned char *key, unsigned char *iv, int enc); |
| 27 void EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, | 37 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, |
| 28 int *outl, unsigned char *in, int inl); 29 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, 30 int *outl); 31 | 38 int *outl, unsigned char *in, int inl); 39 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, 40 int *outl); 41 |
| 32 void EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a); | 42 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen); 43 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr); 44 int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a); |
| 33 34 const EVP_CIPHER *EVP_get_cipherbyname(const char *name); 35 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a)) 36 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a)) 37 38 #define EVP_CIPHER_nid(e) ((e)->nid) 39 #define EVP_CIPHER_block_size(e) ((e)->block_size) 40 #define EVP_CIPHER_key_length(e) ((e)->key_len) | 45 46 const EVP_CIPHER *EVP_get_cipherbyname(const char *name); 47 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a)) 48 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a)) 49 50 #define EVP_CIPHER_nid(e) ((e)->nid) 51 #define EVP_CIPHER_block_size(e) ((e)->block_size) 52 #define EVP_CIPHER_key_length(e) ((e)->key_len) |
| 41 #define EVP_CIPHER_iv_length(e) ((e)->iv_len) 42 | 53 #define EVP_CIPHER_iv_length(e) ((e)->iv_len) 54 #define EVP_CIPHER_flags(e) ((e)->flags) 55 #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE) |
| 43 int EVP_CIPHER_type(const EVP_CIPHER *ctx); | 56 int EVP_CIPHER_type(const EVP_CIPHER *ctx); |
| 57 |
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| 44 #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher) 45 #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid) 46 #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size) | 58 #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher) 59 #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid) 60 #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size) |
| 47 #define EVP_CIPHER_CTX_key_length(e) ((e)->cipher->key_len) | 61 #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len) |
| 48 #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len) | 62 #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len) |
| 63 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data) 64 #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d)) |
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| 49 #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c)) | 65 #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c)) |
| 66 #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags) 67 #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE) |
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| 50 51 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 52 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 53 54=head1 DESCRIPTION 55 56The EVP cipher routines are a high level interface to certain 57symmetric ciphers. 58 | 68 69 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 70 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 71 72=head1 DESCRIPTION 73 74The EVP cipher routines are a high level interface to certain 75symmetric ciphers. 76 |
| 59EVP_EncryptInit() initialises a cipher context B<ctx> for encryption | 77EVP_EncryptInit() initializes a cipher context B<ctx> for encryption |
| 60with cipher B<type>. B<type> is normally supplied by a function such 61as EVP_des_cbc() . B<key> is the symmetric key to use and B<iv> is the 62IV to use (if necessary), the actual number of bytes used for the 63key and IV depends on the cipher. It is possible to set all parameters 64to NULL except B<type> in an initial call and supply the remaining | 78with cipher B<type>. B<type> is normally supplied by a function such 79as EVP_des_cbc() . B<key> is the symmetric key to use and B<iv> is the 80IV to use (if necessary), the actual number of bytes used for the 81key and IV depends on the cipher. It is possible to set all parameters 82to NULL except B<type> in an initial call and supply the remaining |
| 65parameters in subsequent calls. This is normally done when the 66EVP_CIPHER_asn1_to_param() function is called to set the cipher 67parameters from an ASN1 AlgorithmIdentifier and the key from a 68different source. | 83parameters in subsequent calls, all of which have B<type> set to NULL. 84This is done when the default cipher parameters are not appropriate. |
| 69 70EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and 71writes the encrypted version to B<out>. This function can be called 72multiple times to encrypt successive blocks of data. The amount 73of data written depends on the block alignment of the encrypted data: 74as a result the amount of data written may be anything from zero bytes 75to (inl + cipher_block_size - 1) so B<outl> should contain sufficient 76room. The actual number of bytes written is placed in B<outl>. --- 11 unchanged lines hidden (view full) --- 88and restrictions are identical to the encryption operations except that 89the decrypted data buffer B<out> passed to EVP_DecryptUpdate() should 90have sufficient room for (B<inl> + cipher_block_size) bytes unless the 91cipher block size is 1 in which case B<inl> bytes is sufficient. 92 93EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal() are functions 94that can be used for decryption or encryption. The operation performed 95depends on the value of the B<enc> parameter. It should be set to 1 for | 85 86EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and 87writes the encrypted version to B<out>. This function can be called 88multiple times to encrypt successive blocks of data. The amount 89of data written depends on the block alignment of the encrypted data: 90as a result the amount of data written may be anything from zero bytes 91to (inl + cipher_block_size - 1) so B<outl> should contain sufficient 92room. The actual number of bytes written is placed in B<outl>. --- 11 unchanged lines hidden (view full) --- 104and restrictions are identical to the encryption operations except that 105the decrypted data buffer B<out> passed to EVP_DecryptUpdate() should 106have sufficient room for (B<inl> + cipher_block_size) bytes unless the 107cipher block size is 1 in which case B<inl> bytes is sufficient. 108 109EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal() are functions 110that can be used for decryption or encryption. The operation performed 111depends on the value of the B<enc> parameter. It should be set to 1 for |
| 96encryption and 0 for decryption. | 112encryption, 0 for decryption and -1 to leave the value unchanged (the 113actual value of 'enc' being supplied in a previous call). |
| 97 98EVP_CIPHER_CTX_cleanup() clears all information from a cipher context. 99It should be called after all operations using a cipher are complete 100so sensitive information does not remain in memory. 101 102EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 103return an EVP_CIPHER structure when passed a cipher name, a NID or an 104ASN1_OBJECT structure. 105 106EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when 107passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID 108value is an internal value which may not have a corresponding OBJECT 109IDENTIFIER. 110 111EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key 112length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 113structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length | 114 115EVP_CIPHER_CTX_cleanup() clears all information from a cipher context. 116It should be called after all operations using a cipher are complete 117so sensitive information does not remain in memory. 118 119EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 120return an EVP_CIPHER structure when passed a cipher name, a NID or an 121ASN1_OBJECT structure. 122 123EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when 124passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID 125value is an internal value which may not have a corresponding OBJECT 126IDENTIFIER. 127 128EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key 129length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 130structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length |
| 114for all ciphers. | 131for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a 132given cipher, the value of EVP_CIPHER_CTX_key_length() may be different 133for variable key length ciphers. |
| 115 | 134 |
| 135EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx. 136If the cipher is a fixed length cipher then attempting to set the key 137length to any value other than the fixed value is an error. 138 |
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| 116EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV 117length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>. 118It will return zero if the cipher does not use an IV. The constant 119B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers. 120 121EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block 122size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 123structure. The constant B<EVP_MAX_IV_LENGTH> is also the maximum block --- 4 unchanged lines hidden (view full) --- 128IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and 129128 bit RC2 have the same NID. If the cipher does not have an object 130identifier or does not have ASN1 support this function will return 131B<NID_undef>. 132 133EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed 134an B<EVP_CIPHER_CTX> structure. 135 | 139EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV 140length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>. 141It will return zero if the cipher does not use an IV. The constant 142B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers. 143 144EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block 145size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 146structure. The constant B<EVP_MAX_IV_LENGTH> is also the maximum block --- 4 unchanged lines hidden (view full) --- 151IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and 152128 bit RC2 have the same NID. If the cipher does not have an object 153identifier or does not have ASN1 support this function will return 154B<NID_undef>. 155 156EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed 157an B<EVP_CIPHER_CTX> structure. 158 |
| 159EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode: 160EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or 161EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then 162EVP_CIPH_STREAM_CIPHER is returned. 163 |
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| 136EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based 137on the passed cipher. This will typically include any parameters and an 138IV. The cipher IV (if any) must be set when this call is made. This call 139should be made before the cipher is actually "used" (before any 140EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function 141may fail if the cipher does not have any ASN1 support. 142 143EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1 144AlgorithmIdentifier "parameter". The precise effect depends on the cipher 145In the case of RC2, for example, it will set the IV and effective key length. 146This function should be called after the base cipher type is set but before 147the key is set. For example EVP_CipherInit() will be called with the IV and 148key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally 149EVP_CipherInit() again with all parameters except the key set to NULL. It is 150possible for this function to fail if the cipher does not have any ASN1 support 151or the parameters cannot be set (for example the RC2 effective key length | 164EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based 165on the passed cipher. This will typically include any parameters and an 166IV. The cipher IV (if any) must be set when this call is made. This call 167should be made before the cipher is actually "used" (before any 168EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function 169may fail if the cipher does not have any ASN1 support. 170 171EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1 172AlgorithmIdentifier "parameter". The precise effect depends on the cipher 173In the case of RC2, for example, it will set the IV and effective key length. 174This function should be called after the base cipher type is set but before 175the key is set. For example EVP_CipherInit() will be called with the IV and 176key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally 177EVP_CipherInit() again with all parameters except the key set to NULL. It is 178possible for this function to fail if the cipher does not have any ASN1 support 179or the parameters cannot be set (for example the RC2 effective key length |
| 152does not have an B<EVP_CIPHER> structure). | 180is not supported. |
| 153 | 181 |
| 182EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined 183and set. Currently only the RC2 effective key length and the number of rounds of 184RC5 can be set. 185 |
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| 154=head1 RETURN VALUES 155 | 186=head1 RETURN VALUES 187 |
| 156EVP_EncryptInit(), EVP_EncryptUpdate() and EVP_EncryptFinal() do not return 157values. | 188EVP_EncryptInit(), EVP_EncryptUpdate() and EVP_EncryptFinal() return 1 for success 189and 0 for failure. |
| 158 | 190 |
| 159EVP_DecryptInit() and EVP_DecryptUpdate() do not return values. | 191EVP_DecryptInit() and EVP_DecryptUpdate() return 1 for success and 0 for failure. |
| 160EVP_DecryptFinal() returns 0 if the decrypt failed or 1 for success. 161 | 192EVP_DecryptFinal() returns 0 if the decrypt failed or 1 for success. 193 |
| 162EVP_CipherInit() and EVP_CipherUpdate() do not return values. 163EVP_CipherFinal() returns 1 for a decryption failure or 1 for success, if 164the operation is encryption then it always returns 1. | 194EVP_CipherInit() and EVP_CipherUpdate() return 1 for success and 0 for failure. 195EVP_CipherFinal() returns 1 for a decryption failure or 1 for success. |
| 165 | 196 |
| 166EVP_CIPHER_CTX_cleanup() does not return a value. | 197EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure. |
| 167 168EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 169return an B<EVP_CIPHER> structure or NULL on error. 170 171EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID. 172 173EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block 174size. --- 7 unchanged lines hidden (view full) --- 182EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's 183OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER. 184 185EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure. 186 187EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for 188success or zero for failure. 189 | 198 199EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 200return an B<EVP_CIPHER> structure or NULL on error. 201 202EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID. 203 204EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block 205size. --- 7 unchanged lines hidden (view full) --- 213EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's 214OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER. 215 216EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure. 217 218EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for 219success or zero for failure. 220 |
| 221=head1 CIPHER LISTING 222 223All algorithms have a fixed key length unless otherwise stated. 224 225=over 4 226 227=item EVP_enc_null() 228 229Null cipher: does nothing. 230 231=item EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void) 232 233DES in CBC, ECB, CFB and OFB modes respectively. 234 235=item EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void) 236 237Two key triple DES in CBC, ECB, CFB and OFB modes respectively. 238 239=item EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void) 240 241Three key triple DES in CBC, ECB, CFB and OFB modes respectively. 242 243=item EVP_desx_cbc(void) 244 245DESX algorithm in CBC mode. 246 247=item EVP_rc4(void) 248 249RC4 stream cipher. This is a variable key length cipher with default key length 128 bits. 250 251=item EVP_rc4_40(void) 252 253RC4 stream cipher with 40 bit key length. This is obsolete and new code should use EVP_rc4() 254and the EVP_CIPHER_CTX_set_key_length() function. 255 256=item EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void) 257 258IDEA encryption algorithm in CBC, ECB, CFB and OFB modes respectively. 259 260=item EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void) 261 262RC2 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key 263length cipher with an additional parameter called "effective key bits" or "effective key length". 264By default both are set to 128 bits. 265 266=item EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void) 267 268RC2 algorithm in CBC mode with a default key length and effective key length of 40 and 64 bits. 269These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and 270EVP_CIPHER_CTX_ctrl() to set the key length and effective key length. 271 272=item EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void); 273 274Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key 275length cipher. 276 277=item EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void) 278 279CAST encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key 280length cipher. 281 282=item EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void) 283 284RC5 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key length 285cipher with an additional "number of rounds" parameter. By default the key length is set to 128 286bits and 12 rounds. 287 288=back 289 |
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| 190=head1 NOTES 191 192Where possible the B<EVP> interface to symmetric ciphers should be used in 193preference to the low level interfaces. This is because the code then becomes 194transparent to the cipher used and much more flexible. 195 196PKCS padding works by adding B<n> padding bytes of value B<n> to make the total 197length of the encrypted data a multiple of the block size. Padding is always 198added so if the data is already a multiple of the block size B<n> will equal 199the block size. For example if the block size is 8 and 11 bytes are to be 200encrypted then 5 padding bytes of value 5 will be added. 201 202When decrypting the final block is checked to see if it has the correct form. 203 204Although the decryption operation can produce an error, it is not a strong 205test that the input data or key is correct. A random block has better than 2061 in 256 chance of being of the correct format and problems with the 207input data earlier on will not produce a final decrypt error. 208 | 290=head1 NOTES 291 292Where possible the B<EVP> interface to symmetric ciphers should be used in 293preference to the low level interfaces. This is because the code then becomes 294transparent to the cipher used and much more flexible. 295 296PKCS padding works by adding B<n> padding bytes of value B<n> to make the total 297length of the encrypted data a multiple of the block size. Padding is always 298added so if the data is already a multiple of the block size B<n> will equal 299the block size. For example if the block size is 8 and 11 bytes are to be 300encrypted then 5 padding bytes of value 5 will be added. 301 302When decrypting the final block is checked to see if it has the correct form. 303 304Although the decryption operation can produce an error, it is not a strong 305test that the input data or key is correct. A random block has better than 3061 in 256 chance of being of the correct format and problems with the 307input data earlier on will not produce a final decrypt error. 308 |
| 309The functions EVP_EncryptInit(), EVP_EncryptUpdate(), EVP_EncryptFinal(), 310EVP_DecryptInit(), EVP_DecryptUpdate(), EVP_CipherInit() and EVP_CipherUpdate() 311and EVP_CIPHER_CTX_cleanup() did not return errors in OpenSSL version 0.9.5a or 312earlier. Software only versions of encryption algorithms will never return 313error codes for these functions, unless there is a programming error (for example 314and attempt to set the key before the cipher is set in EVP_EncryptInit() ). 315 |
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| 209=head1 BUGS 210 | 316=head1 BUGS 317 |
| 211The current B<EVP> cipher interface is not as flexible as it should be. Only 212certain "spot" encryption algorithms can be used for ciphers which have various 213parameters associated with them (RC2, RC5 for example) this is inadequate. | 318For RC5 the number of rounds can currently only be set to 8, 12 or 16. This is 319a limitation of the current RC5 code rather than the EVP interface. |
| 214 | 320 |
| 215Several of the functions do not return error codes because the software versions 216can never fail. This is not true of hardware versions. | 321It should be possible to disable PKCS padding: currently it isn't. |
| 217 | 322 |
| 323EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with 324default key lengths. If custom ciphers exceed these values the results are 325unpredictable. This is because it has become standard practice to define a 326generic key as a fixed unsigned char array containing EVP_MAX_KEY_LENGTH bytes. 327 328The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested 329for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode. 330 331=head1 EXAMPLES 332 333Get the number of rounds used in RC5: 334 335 int nrounds; 336 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &i); 337 338Get the RC2 effective key length: 339 340 int key_bits; 341 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &i); 342 343Set the number of rounds used in RC5: 344 345 int nrounds; 346 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, i, NULL); 347 348Set the number of rounds used in RC2: 349 350 int nrounds; 351 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, i, NULL); 352 |
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| 218=head1 SEE ALSO 219 220L<evp(3)|evp(3)> 221 222=head1 HISTORY 223 224=cut | 353=head1 SEE ALSO 354 355L<evp(3)|evp(3)> 356 357=head1 HISTORY 358 359=cut |