一、简介
asn1parse命令是一种用来诊断ASN.1结构的工具，也能用于从ASN1.1数据中提取数据
二、语法
openssl asn1parse [-inform PEM|DER] [-in filename] [-out filename] [-noout] [-offset number] [-length number] [-i] [- structure filename] [-strparse offset]选项
-inform arg input format - one of DER PEM -in arg input file -out arg output file (output format is always DER -noout arg don't produce any output -offset arg offset into file -length arg length of section in file -i indent entries -dump dump unknown data in hex form -dlimit arg dump the first arg bytes of unknown data in hex form -oid file file of extra oid definitions -strparse offset a series of these can be used to 'dig' into multiple ASN1 blob wrappings -genstr str string to generate ASN1 structure from -genconf file file to generate ASN1 structure from
三、ASN.1结构
0:d=0 hl=4 l= 710 cons: SEQUENCE
0 表示节点在整个文件中的偏移长度 d=0 表示节点深度 hl=4 表示节点头字节长度 l=710 表示节点数据字节长度 cons 表示该节点为结构节点，表示包含子节点或者子结构数据 prim 表示该节点为原始节点，包含数据 SEQUENCE、OCTETSTRING等都是ASN.1中定义的数据类型，具体可以参考ASN.1格式说明。 最后一个节点OCTET STRING [HEX DUMP]，就是加密后的私钥数据。
四、实例
1）分析一个文件
openssl asn1parse -in ec_pubkey.pem
2）分析一个DER文件
openssl asn1parse -inform DER -in file.der
3）解析公钥文件
openssl x509 -in cert.pem -pubkey -noout > pubkey.key
移除pem头尾后进行base64解码: openssl base64 x -in pubkey.key -out pubkey.bin
openssl asn1parse -in pubkey.key
0:d=0 hl=3 l= 159 cons: SEQUENCE
3:d=1 hl=2 l= 13 cons: SEQUENCE
5:d=2 hl=2 l= 9 prim: OBJECT :rsaEncryption
16:d=2 hl=2 l= 0 prim: NULL
18:d=1 hl=3 l= 141 prim: BIT STRING
openssl asn1parse -strparse 18 -in pubkey.key
0:d=0 hl=3 l= 137 cons: SEQUENCE
3:d=1 hl=3 l= 129 prim: INTEGER :BD08016AC47043B12704EF63B82AA311204A627C550CB5E0B44FBF70731F5A19C3E1FAA36F8E52F6C8A673F3704B0A3F1888F665EBFB257D5689F36F805F2C7442A0E0F90B1E3542A08C5E347FA21
DE6CE84A572BAAC892DE8AF611B5B2F81E8DA3EEA6E6C92A488876DF0B9DD9CEECC2A22D0C985904F40740FFF49836DE2B7
135:d=1 hl=2 l= 3 prim: INTEGER :010001
