YAAES

VHDL implementation of the symmetric block cipher AES, as specified in the NIST FIPS 197, respectively NIST SP 800-38A.

Features:

• Interface width of 8, 32 and 128 bit.
• Key width of 128 and 256 bit, i. e. AES-128 and AES-256.
• The following modes:

Development status:

• VHDL design
• Functional simulation
• Implementation
• Test on FPGA (it was reported that the design was successfully ran on an Altera Max 10 Board at 50 MHz)

Usage

The core expects key, iv (optional) and plaintext/ciphertext (depending if encrypting or decrypting) through islv_data. A new set of key and iv should be signalised by assigning isl_new_key_iv for one cycle. Valid inputs should be marked by assigning the isl_valid signal. Accordingly, the output oslv_data is valid when the signal osl_valid is assigned. New input data can be transmitted only when the output is fully done.

Example for AES-256 encryption in CFB mode with an interface bitwidth of 32 bit:

Resource usage

The following results are obtained from a local synthesis for Lattice ECP5, using the open source toolchain (ghdl, yosys and nextpnr). For more details, see the synthesis workflow.

• Device: ULX3S
• Configuration: as in the example above
• Results:
  • Resources:
    • TRELLIS_SLICE: 3109/41820 7%
    • DCCA: 1/ 56 1%
  • Target frequency: 100 MHz
  • Maximum frequency: 121 MHz

Performance

From the testsuite runs, the following metrics can be derived (configuration as above):

• Latency: 37 cycles (after initial key and iv transmission)
• Throughput: One input of 128 bit each 42 cycles → 3 bit per clock cycle → 300 Mbps at 100 MHz