cbc.c File Reference

Cipher-block chaining. More...

#include <string.h>
#include <assert.h>
#include <ipxe/crypto.h>
#include <ipxe/cbc.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static void	cbc_xor (const void *src, void *dst, size_t len)
	XOR data blocks. More...
void	cbc_encrypt (void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
	Encrypt data. More...
void	cbc_decrypt (void *ctx, const void *src, void *dst, size_t len, struct cipher_algorithm *raw_cipher, void *cbc_ctx)
	Decrypt data. More...

Detailed Description

Cipher-block chaining.

Definition in file cbc.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

cbc_xor()

static void cbc_xor ( const void *  src, void *  dst, size_t  len  )

static

XOR data blocks.

Parameters

src	Input data
dst	Second input data and output data buffer
len	Length of data

Definition at line 44 of file cbc.c.

                                                               {
        const uint32_t *srcl = src;
        uint32_t *dstl = dst;
        unsigned int i;

        /* Assume that block sizes will always be dword-aligned, for speed */
        assert ( ( len % sizeof ( *srcl ) ) == 0 );

        for ( i = 0 ; i < ( len / sizeof ( *srcl ) ) ; i++ )
                dstl[i] ^= srcl[i];
}

References assert(), dst, len, and src.

Referenced by cbc_decrypt(), and cbc_encrypt().

cbc_encrypt()

void cbc_encrypt	(	void *	ctx,
		const void *	src,
		void *	dst,
		size_t	len,
		struct cipher_algorithm *	raw_cipher,
		void *	cbc_ctx
	)

Encrypt data.

Parameters

ctx	Context
src	Data to encrypt
dst	Buffer for encrypted data
len	Length of data
raw_cipher	Underlying cipher algorithm
cbc_ctx	CBC context

Definition at line 66 of file cbc.c.

                                                                        {
        size_t blocksize = raw_cipher->blocksize;

        assert ( ( len % blocksize ) == 0 );

        while ( len ) {
                cbc_xor ( src, cbc_ctx, blocksize );
                cipher_encrypt ( raw_cipher, ctx, cbc_ctx, dst, blocksize );
                memcpy ( cbc_ctx, dst, blocksize );
                dst += blocksize;
                src += blocksize;
                len -= blocksize;
        }
}

References assert(), cipher_algorithm::blocksize, cbc_xor(), cipher_encrypt, ctx, dst, len, memcpy(), and src.

cbc_decrypt()

void cbc_decrypt	(	void *	ctx,
		const void *	src,
		void *	dst,
		size_t	len,
		struct cipher_algorithm *	raw_cipher,
		void *	cbc_ctx
	)

Decrypt data.

Parameters

ctx	Context
src	Data to decrypt
dst	Buffer for decrypted data
len	Length of data
raw_cipher	Underlying cipher algorithm
cbc_ctx	CBC context

Definition at line 92 of file cbc.c.

                                                                        {
        size_t blocksize = raw_cipher->blocksize;
        uint8_t next_cbc_ctx[blocksize];

        assert ( ( len % blocksize ) == 0 );

        while ( len ) {
                memcpy ( next_cbc_ctx, src, blocksize );
                cipher_decrypt ( raw_cipher, ctx, src, dst, blocksize );
                cbc_xor ( cbc_ctx, dst, blocksize );
                memcpy ( cbc_ctx, next_cbc_ctx, blocksize );
                dst += blocksize;
                src += blocksize;
                len -= blocksize;
        }
}

References assert(), cipher_algorithm::blocksize, cbc_xor(), cipher_decrypt, ctx, dst, len, memcpy(), and src.