This is the same test as rsa-pkcs1-sha256.pem except the SPKI has been encoded using a non-minimal length for the outtermost SEQUENCE. Under DER, the tag-length-value encodings should be minimal and hence this should fail. Specifically the SPKI start was changed from: 30 81 9f To: 30 82 00 9f (the length of 0x9F is being expressed using 2 bytes instead of 1) -----BEGIN PUBLIC KEY----- MIIAnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAqkfgdjI9YqzadSZ2Ns0CEEUD8+8m7OplIx0 94X+QD8mooNrunwT04asbLIINGL4qiI/+9IVSvyV3Kj9c4EeQIbANGoJ8AI3wf6MOBB/txxGFed qqcTffKVMQvtZdoYFbZ/MQkvyRsoyvunb/pWcN4sSaF9kY1bXSeP3J99fBIYUCAwEAAQ== -----END PUBLIC KEY----- $ openssl asn1parse -i < [PUBLIC KEY] 0:d=0 hl=4 l= 159 cons: SEQUENCE 4:d=1 hl=2 l= 13 cons: SEQUENCE 6:d=2 hl=2 l= 9 prim: OBJECT :rsaEncryption 17:d=2 hl=2 l= 0 prim: NULL 19:d=1 hl=3 l= 141 prim: BIT STRING -----BEGIN ALGORITHM----- MA0GCSqGSIb3DQEBCwUA -----END ALGORITHM----- $ openssl asn1parse -i < [ALGORITHM] 0:d=0 hl=2 l= 13 cons: SEQUENCE 2:d=1 hl=2 l= 9 prim: OBJECT :sha256WithRSAEncryption 13:d=1 hl=2 l= 0 prim: NULL -----BEGIN DATA----- MIIB46ADAgECAgkA3l4tFOVii0UwDQYJKoZIhvcNAQELBQAwVjELMAkGA1UEBhMCQVUxEzARBgN VBAgMClNvbWUtU3RhdGUxITAfBgNVBAoMGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEPMA0GA1 UEAwwGTXkga2V5MB4XDTE1MDcwMjE3MDYzOVoXDTE2MDcwMTE3MDYzOVowVjELMAkGA1UEBhMCQ VUxEzARBgNVBAgMClNvbWUtU3RhdGUxITAfBgNVBAoMGEludGVybmV0IFdpZGdpdHMgUHR5IEx0 ZDEPMA0GA1UEAwwGTXkga2V5MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCqR+B2Mj1irNp 1JnY2zQIQRQPz7ybs6mUjHT3hf5APyaig2u6fBPThqxssgg0YviqIj/70hVK/JXcqP1zgR5AhsA 0agnwAjfB/ow4EH+3HEYV52qpxN98pUxC+1l2hgVtn8xCS/JGyjK+6dv+lZw3ixJoX2RjVtdJ4/ cn318EhhQIDAQABo1AwTjAdBgNVHQ4EFgQUzQBVKTEknyLndWd2HTsBdTKvyikwHwYDVR0jBBgw FoAUzQBVKTEknyLndWd2HTsBdTKvyikwDAYDVR0TBAUwAwEB/w== -----END DATA----- -----BEGIN SIGNATURE----- A4GBADrHSmFSJw/Gv7hs5PNzpaJwAri/sitarIZfzN/SjR+n8L8yeTEoiDb1+BkxlFvXvPHTaOK oO3WlslNNOxh1W5/JkYYGOUkCcyIjnln6qS560imcr3VNjomT/M8M2Iss+rJiKau1TRuaP7H8i6 +Gqf3saGdr8/LnvFAdNQvkalQt -----END SIGNATURE----- $ openssl asn1parse -i < [SIGNATURE] 0:d=0 hl=3 l= 129 prim: BIT STRING