CSR Example
The PKCS#10 standard defines a binary format for encoding CSRs for use with X.509. It is expressed in ASN.1. Here is an example of how you can examine its ASN.1 structure using OpenSSL:
openssl asn1parse -in your_request
A CSR may be represented as a Base64 encoded PKCS#10; an example of which is given below:
-----BEGIN CERTIFICATE REQUEST----- MIIBnTCCAQYCAQAwXTELMAkGA1UEBhMCU0cxETAPBgNVBAoTCE0yQ3J5cHRvMRIw EAYDVQQDEwlsb2NhbGhvc3QxJzAlBgkqhkiG9w0BCQEWGGFkbWluQHNlcnZlci5l eGFtcGxlLmRvbTCBnzANBgkqhkiG9w0BAQEFAAOBjQAwgYkCgYEAr1nYY1Qrll1r uB/FqlCRrr5nvupdIN+3wF7q915tvEQoc74bnu6b8IbbGRMhzdzmvQ4SzFfVEAuM MuTHeybPq5th7YDrTNizKKxOBnqE2KYuX9X22A1Kh49soJJFg6kPb9MUgiZBiMlv tb7K3CHfgw5WagWnLl8Lb+ccvKZZl+8CAwEAAaAAMA0GCSqGSIb3DQEBBAUAA4GB AHpoRp5YS55CZpy+wdigQEwjL/wSluvo+WjtpvP0YoBMJu4VMKeZi405R7o8oEwi PdlrrliKNknFmHKIaCKTLRcU59ScA6ADEIWUzqmUzP5Cs6jrSRo3NKfg1bd09D1K 9rsQkRc9Urv9mRBIsredGnYECNeRaK5R1yzpOowninXC -----END CERTIFICATE REQUEST-----The above certificate signing request's ASN.1 structure (as parsed by openssl) appears as the following:
0:d=0 hl=4 l= 413 cons: SEQUENCE 4:d=1 hl=4 l= 262 cons: SEQUENCE 8:d=2 hl=2 l= 1 prim: INTEGER :00 11:d=2 hl=2 l= 93 cons: SEQUENCE 13:d=3 hl=2 l= 11 cons: SET 15:d=4 hl=2 l= 9 cons: SEQUENCE 17:d=5 hl=2 l= 3 prim: OBJECT :countryName 22:d=5 hl=2 l= 2 prim: PRINTABLESTRING :SG 26:d=3 hl=2 l= 17 cons: SET 28:d=4 hl=2 l= 15 cons: SEQUENCE 30:d=5 hl=2 l= 3 prim: OBJECT :organizationName 35:d=5 hl=2 l= 8 prim: PRINTABLESTRING :M2Crypto 45:d=3 hl=2 l= 18 cons: SET 47:d=4 hl=2 l= 16 cons: SEQUENCE 49:d=5 hl=2 l= 3 prim: OBJECT :commonName 54:d=5 hl=2 l= 9 prim: PRINTABLESTRING :localhost 65:d=3 hl=2 l= 39 cons: SET 67:d=4 hl=2 l= 37 cons: SEQUENCE 69:d=5 hl=2 l= 9 prim: OBJECT :emailAddress 80:d=5 hl=2 l= 24 prim: IA5STRING :admin@server.example.dom 106:d=2 hl=3 l= 159 cons: SEQUENCE 109:d=3 hl=2 l= 13 cons: SEQUENCE 111:d=4 hl=2 l= 9 prim: OBJECT :rsaEncryption 122:d=4 hl=2 l= 0 prim: NULL 124:d=3 hl=3 l= 141 prim: BIT STRING 268:d=2 hl=2 l= 0 cons: cont 270:d=1 hl=2 l= 13 cons: SEQUENCE 272:d=2 hl=2 l= 9 prim: OBJECT :md5WithRSAEncryption 283:d=2 hl=2 l= 0 prim: NULL 285:d=1 hl=3 l= 129 prim: BIT STRING(This was generated by supplying the base64 encoding into the command openssl asn1parse -in your_request -inform PEM -i where PEM stands for Privacy-enhanced mail and describes the encoding of the ASN.1 Distinguished Encoding Rules in base64.)
Read more about this topic: Certificate Signing Request