spdm-responder fails on signature generation

[leongross]

Running the responder example eventually fails.

$ cargo run --example spdm_responder -- --verbose                                                          
...
Successfully processed SPDM message
Error processing SPDM message: Transport(ReceiveError)
Connection closed gracefully

Inspecting the corresponding spdm-emu requester reveals that the challenge signature verification fails:

...
libspdm_receive_spdm_response[0] msg SPDM_CHALLENGE_AUTH(0x3), size (0xe6): 
0000: 12 03 00 01 04 81 c0 e4 4c 1b 21 a9 61 a7 32 f9 6b 70 73 6a f3 2c 41 2b bd ca 7f 4b dd f3 b8 03 
0020: 43 c5 88 a8 17 17 54 eb 62 64 26 5c 74 bd 1d c5 10 3e 0a 88 43 04 c5 86 47 08 c9 8a 4b 0c cd 8e 
0040: 4f 10 d1 92 53 14 d5 96 57 18 d9 9a 5b 1c dd 9e 5f 20 e1 a2 65 3b 3f 7b 29 4e 06 dc db 05 26 d8 
0060: 5f e2 41 8e 23 21 ec 34 a9 4e 92 cd 77 f9 92 4d 9b 11 ae 72 a6 e1 13 fb bf c8 9b 8e 83 93 61 33 
0080: 50 7e a0 2a 00 00 2b fe 25 76 b3 2f c7 dd 7a 2b ed c2 44 81 de e8 68 d5 5a 84 b0 cc 33 84 61 ae 
00a0: fe 13 03 ef cc fe 28 0d df a7 c8 aa ef ab 5f 04 d9 be c0 fd 8b 80 08 92 2e ea d6 a0 6f 67 83 b9 
00c0: b2 00 f8 20 d4 8d 53 df ea ad ab 52 17 1d a1 a8 11 a3 76 62 41 b5 d4 3c 62 ef 52 b2 f8 a7 75 ea 
00e0: ad 7f ac a0 b5 d0 
cert_chain_hash (0x30) - 04 81 c0 e4 4c 1b 21 a9 61 a7 32 f9 6b 70 73 6a f3 2c 41 2b bd ca 7f 4b dd f3 b8 03 43 c5 88 a8 17 17 54 eb 62 64 26 5c 74 bd 1d c5 10 3e 0a 88 
!!! verify_certificate_chain_hash - PASS !!!
nonce (0x20) - 43 04 c5 86 47 08 c9 8a 4b 0c cd 8e 4f 10 d1 92 53 14 d5 96 57 18 d9 9a 5b 1c dd 9e 5f 20 e1 a2 
measurement_summary_hash (0x30) - 65 3b 3f 7b 29 4e 06 dc db 05 26 d8 5f e2 41 8e 23 21 ec 34 a9 4e 92 cd 77 f9 92 4d 9b 11 ae 72 a6 e1 13 fb bf c8 9b 8e 83 93 61 33 50 7e a0 2a 
signature (0x60):
0000: 2b fe 25 76 b3 2f c7 dd 7a 2b ed c2 44 81 de e8 68 d5 5a 84 b0 cc 33 84 61 ae fe 13 03 ef cc fe 
0020: 28 0d df a7 c8 aa ef ab 5f 04 d9 be c0 fd 8b 80 08 92 2e ea d6 a0 6f 67 83 b9 b2 00 f8 20 d4 8d 
0040: 53 df ea ad ab 52 17 1d a1 a8 11 a3 76 62 41 b5 d4 3c 62 ef 52 b2 f8 a7 75 ea ad 7f ac a0 b5 d0 
m1m2 hash - 44 68 9f 53 1a e4 c2 72 30 02 25 d6 0d 2a 99 79 5a 08 82 fd 13 63 e0 d5 02 f7 af 19 ab cc a1 97 5b ef f1 47 98 17 ec 1b 64 6b 1f f8 e1 a8 73 dc 
!!! verify_challenge_signature - FAIL !!!