cryptography - Get key parameters from imported Elliptic Curve key in ASN.1 format -


i need write code gets input elliptic curve key in asn.1 format.

the input byte array next:

308187020100301306072a8648ce3d020106082a8648ce3d030107046d306b0201010420e699203ac5bcfe36402ebd0ac9e8e21cc6fad5828a61297ea747468fff4dbb20a144034200047e05188a03ea81e853b9f6ac5f20dca1a1ca828fd7cd5d92161fb2120c35eac52eab079ed01a510123057c322ddff95e239d6063055bc90858d161d71de707f8

online parser shows me next structure:

result of online asn.1 parser

to use key want need public value x, public value y , private value structure, @ least think so. not know how.

i have searched information object identifier 1.2.840.10045.2.1 , object identifier 1.2.840.10045.3.1.7. i've found this document. there no description of fields of asn.1 structure.

how can required parameters imported data?

it's commonly known pkcs#8 structure, "private-key information syntax specification". contains unencrypted part of pkcs#8 private key.

so in pkcs#8:

privatekeyinfo ::= sequence {     version version,     privatekeyalgorithm algorithmidentifier {{privatekeyalgorithms}},     privatekey privatekey,     attributes [0] attributes optional }

the algorithmidentifier taken pkcs#5

algorithmidentifier { algorithm-identifier:infoobjectset } ::= sequence {     algorithm algorithm-identifier.&id({infoobjectset}),     parameters algorithm-identifier.&type({infoobjectset}     {@algorithm}) optional }

the elliptic curve private key structure:

ecprivatekey ::= sequence {     version        integer { ecprivkeyver1(1) } (ecprivkeyver1),     privatekey     octet string,     parameters [0] ecparameters {{ namedcurve }} optional,     publickey  [1] bit string optional }

oh, , encoded in der, distinguished encoding rules (study version) - may not able rule out ber completely, more loosely defined , therefore harder parse structure). pkcs#8 defines ber unfortunately.

oh, yeah, public key in uncompressed point format. don't forget strip away 00 bit string.

happy parsing.


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