How to view the ASN.1 structure of an RSA public key using the OpenSSL "asn1parse" command?

You can use the OpenSSL "asn1parse" command to view the ASN.1 structure of an RSA public key as shown in the test below:

C:\Users\fyicenter>\local\openssl\openssl 
   pkey -in rsa_pri.key -pubout -out rsa_pub.key

C:\Users\fyicenter>\local\openssl\openssl 
   asn1parse -in rsa_pub.key -i
    0:d=0  hl=2 l=  92 cons: SEQUENCE
    2:d=1  hl=2 l=  13 cons:  SEQUENCE
    4:d=2  hl=2 l=   9 prim:   OBJECT            :rsaEncryption
   15:d=2  hl=2 l=   0 prim:   NULL
   17:d=1  hl=2 l=  75 prim:  BIT STRING
   
C:\Users\fyicenter>\local\openssl\openssl 
   asn1parse -in rsa_pub.key -strparse 17
    0:d=0  hl=2 l=  72 cons: SEQUENCE
    2:d=1  hl=2 l=  65 prim: INTEGER           :98872AF758AD6325645AA989ED59ABF2
AA4200F6DE59C1D5567A343B8852E32A9EA593559142A0EDD535916D03490EAF324C3E6A973A7161
E5D28E355E5E1E03
   69:d=1  hl=2 l=   3 prim: INTEGER           :010001
   
C:\Users\fyicenter>\local\openssl\openssl 
   pkey -pubin -in rsa_pub.key -text -noout
Public-Key: (512 bit)
Modulus:
    00:98:87:2a:f7:58:ad:63:25:64:5a:a9:89:ed:59:
    ab:f2:aa:42:00:f6:de:59:c1:d5:56:7a:34:3b:88:
    52:e3:2a:9e:a5:93:55:91:42:a0:ed:d5:35:91:6d:
    03:49:0e:af:32:4c:3e:6a:97:3a:71:61:e5:d2:8e:
    35:5e:5e:1e:03
Exponent: 65537 (0x10001)   

Note about the test:

• A RSA public key is stored in an ASN.1 structure starting with root SEQUENCE, which includes a sub SEQUENCE and a BIT STRING.
• The sub SEQUENCE contains the OID of the RSA algorithm and a NULL field.
• The BIT STRING wraps a hidden SEQUENCE that has 2 INTEGER fields representing the RSA public components.

⇒ OpenSSL "ans1parse" - Configuration File for RSA Public Key

⇐ OpenSSL "ans1parse" - Configuration File for RSA Private Key

⇑ OpenSSL "ans1parse" Command

⇑⇑ OpenSSL Tutorials