1087
6437E–ATARM–23-Apr-13
SAM9M11
45. Triple Data Encryption Standard (TDES)
45.1
Description
The Triple Data Encryption Standard (TDES) is compliant with the American FIPS (Federal
Information Processing Standard) Publication 46-3 specification.
The TDES supports the four different confidentiality modes of operation (ECB, CBC, OFB and
CFB), specified in the FIPS (Federal Information Processing Standard) Publication 81 and is
compatible with the Peripheral Data Controller channels for all of these modes, minimizing pro-
cessor intervention for large buffer transfers.
The 64-bit long keys and input data (and initialization vector for some modes) are each stored in
two 32-bit registers (TDES_KEYxWxR, TDES_IDATAxR and TDES_IVxR) which are both write-
only.
As soon as the initialization vector, the input data and the key are configured, the encryp-
tion/decryption process may be started. Then the encrypted/decrypted data is ready to be read
out on the two 32-bit output data registers (TDES_ODATAxR) or through the PDC channels.
45.2
Embedded Characteristics
Supports Single Data Encryption Standard (DES) and Triple Data Encryption Algorithm
(TDEA or TDES)
Compliant with FIPS Publication 46-3, Data Encryption Standard (DES)
64-bit Cryptographic Key for TDES
Two-key or Three-key Algorithms for TDES
18-clock Cycles Encryption/Decryption Processing Time for DES
50-clock Cycles Encryption/Decryption Processing Time for TDES
Support the Four Standard Modes of Operation specified in the FIPS Publication 81, DES
Modes of Operation
– Electronic Code Book (ECB)
– Cipher Block Chaining (CBC)
– Cipher Feedback (CFB)
– Output Feedback (OFB)
8-, 16-, 32-, 64- and 128-bit Data Sizes Possible in CFB Mode
Last Output Data Mode Allows Optimized Message (Data) Authentication Code (MAC)
Generation
Connection to PDC Channel Capabilities Optimizes Data Transfers for all Operating Modes
– One Channel for the Receiver, One Channel for the Transmitter
– Next Buffer Support