diff options
Diffstat (limited to 'crypto/openssl/doc/crypto/EVP_EncryptInit.pod')
| -rw-r--r-- | crypto/openssl/doc/crypto/EVP_EncryptInit.pod | 65 |
1 files changed, 29 insertions, 36 deletions
diff --git a/crypto/openssl/doc/crypto/EVP_EncryptInit.pod b/crypto/openssl/doc/crypto/EVP_EncryptInit.pod index 8271d3dfc417..ed027b387aea 100644 --- a/crypto/openssl/doc/crypto/EVP_EncryptInit.pod +++ b/crypto/openssl/doc/crypto/EVP_EncryptInit.pod @@ -115,7 +115,7 @@ writes the encrypted version to B<out>. This function can be called multiple times to encrypt successive blocks of data. The amount of data written depends on the block alignment of the encrypted data: as a result the amount of data written may be anything from zero bytes -to (inl + cipher_block_size - 1) so B<outl> should contain sufficient +to (inl + cipher_block_size - 1) so B<out> should contain sufficient room. The actual number of bytes written is placed in B<outl>. If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts @@ -152,7 +152,7 @@ does not remain in memory. EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex and -EVP_CipherInit_ex() except the B<ctx> paramter does not need to be +EVP_CipherInit_ex() except the B<ctx> parameter does not need to be initialized and they always use the default cipher implementation. EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() behave in a @@ -344,7 +344,10 @@ bits and 12 rounds. Where possible the B<EVP> interface to symmetric ciphers should be used in preference to the low level interfaces. This is because the code then becomes -transparent to the cipher used and much more flexible. +transparent to the cipher used and much more flexible. Additionally, the +B<EVP> interface will ensure the use of platform specific cryptographic +acceleration such as AES-NI (the low level interfaces do not provide the +guarantee). PKCS padding works by adding B<n> padding bytes of value B<n> to make the total length of the encrypted data a multiple of the block size. Padding is always @@ -384,27 +387,7 @@ for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode. =head1 EXAMPLES -Get the number of rounds used in RC5: - - int nrounds; - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &nrounds); - -Get the RC2 effective key length: - - int key_bits; - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &key_bits); - -Set the number of rounds used in RC5: - - int nrounds; - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, nrounds, NULL); - -Set the effective key length used in RC2: - - int key_bits; - EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, key_bits, NULL); - -Encrypt a string using blowfish: +Encrypt a string using IDEA: int do_crypt(char *outfile) { @@ -418,8 +401,9 @@ Encrypt a string using blowfish: char intext[] = "Some Crypto Text"; EVP_CIPHER_CTX ctx; FILE *out; + EVP_CIPHER_CTX_init(&ctx); - EVP_EncryptInit_ex(&ctx, EVP_bf_cbc(), NULL, key, iv); + EVP_EncryptInit_ex(&ctx, EVP_idea_cbc(), NULL, key, iv); if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext))) { @@ -448,28 +432,34 @@ Encrypt a string using blowfish: } The ciphertext from the above example can be decrypted using the B<openssl> -utility with the command line: +utility with the command line (shown on two lines for clarity): - S<openssl bf -in cipher.bin -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -d> + openssl idea -d <filename + -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -General encryption, decryption function example using FILE I/O and RC2 with an -80 bit key: +General encryption and decryption function example using FILE I/O and AES128 +with a 128-bit key: int do_crypt(FILE *in, FILE *out, int do_encrypt) { /* Allow enough space in output buffer for additional block */ - inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; + unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; int inlen, outlen; + EVP_CIPHER_CTX ctx; /* Bogus key and IV: we'd normally set these from * another source. */ - unsigned char key[] = "0123456789"; - unsigned char iv[] = "12345678"; - /* Don't set key or IV because we will modify the parameters */ + unsigned char key[] = "0123456789abcdeF"; + unsigned char iv[] = "1234567887654321"; + + /* Don't set key or IV right away; we want to check lengths */ EVP_CIPHER_CTX_init(&ctx); - EVP_CipherInit_ex(&ctx, EVP_rc2(), NULL, NULL, NULL, do_encrypt); - EVP_CIPHER_CTX_set_key_length(&ctx, 10); - /* We finished modifying parameters so now we can set key and IV */ + EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL, + do_encrypt); + OPENSSL_assert(EVP_CIPHER_CTX_key_length(&ctx) == 16); + OPENSSL_assert(EVP_CIPHER_CTX_iv_length(&ctx) == 16); + + /* Now we can set key and IV */ EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt); for(;;) @@ -508,4 +498,7 @@ EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex(), EVP_CipherFinal_ex() and EVP_CIPHER_CTX_set_padding() appeared in OpenSSL 0.9.7. +IDEA appeared in OpenSSL 0.9.7 but was often disabled due to +patent concerns; the last patents expired in 2012. + =cut |