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[crypto] Allow creation of arbitrary CBC cipher algorithms using CBC_CIPHER()

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Given any block cipher, a corresponding CBC mode of behaviour for the
cipher can be created using the CBC_CIPHER() macro.
This commit is contained in:
Michael Brown
2009-02-19 01:48:52 +00:00
parent e950dc04ba
commit 9937bf13c9
3 changed files with 66 additions and 106 deletions
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16
src/crypto/cbc.c
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@@ -53,18 +53,18 @@ static void cbc_xor ( const void *src, void *dst, size_t len ) {
* @v src Data to encrypt
* @v dst Buffer for encrypted data
* @v len Length of data
* @v cipher Underlying cipher algorithm
* @v raw_cipher Underlying cipher algorithm
* @v cbc_ctx CBC context
*/
void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len,
struct cipher_algorithm *cipher, void *cbc_ctx ) {
size_t blocksize = cipher->blocksize;
struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
size_t blocksize = raw_cipher->blocksize;
assert ( ( len % blocksize ) == 0 );
while ( len ) {
cbc_xor ( src, cbc_ctx, blocksize );
cipher_encrypt ( cipher, ctx, cbc_ctx, dst, blocksize );
cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
memcpy ( cbc_ctx, dst, blocksize );
dst += blocksize;
src += blocksize;
@@ -79,17 +79,17 @@ void cbc_encrypt ( void *ctx, const void *src, void *dst, size_t len,
* @v src Data to decrypt
* @v dst Buffer for decrypted data
* @v len Length of data
* @v cipher Underlying cipher algorithm
* @v raw_cipher Underlying cipher algorithm
* @v cbc_ctx CBC context
*/
void cbc_decrypt ( void *ctx, const void *src, void *dst, size_t len,
struct cipher_algorithm *cipher, void *cbc_ctx ) {
size_t blocksize = cipher->blocksize;
struct cipher_algorithm *raw_cipher, void *cbc_ctx ) {
size_t blocksize = raw_cipher->blocksize;
assert ( ( len % blocksize ) == 0 );
while ( len ) {
cipher_decrypt ( cipher, ctx, src, dst, blocksize );
cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
cbc_xor ( cbc_ctx, dst, blocksize );
memcpy ( cbc_ctx, src, blocksize );
dst += blocksize;