PowerBuilder

Understanding a few ECDSA Public Key Formats

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Describes a few ECDSA public key formats. PowerBuilder

integer li_rc
integer li_Success
oleobject loo_SbPem
oleobject loo_PubKey1
oleobject loo_SbHex
integer li_NumReplaced
oleobject loo_BdKey
oleobject loo_PubKey2

li_Success = 0

// Here we have the output of the following openssl command:  openssl ec -in key.pem -pubout -text

// Private-Key: (256 bit)
// priv:
//     0e:63:25:8a:73:3c:71:b6:c0:e7:a3:0f:94:b9:74:
//     e0:be:bd:46:18:be:40:7e:66:9e:21:99:85:0e:ed:
//     87:2d
// pub:
//     04:5d:1a:4f:d9:bd:49:9e:e4:fd:55:2c:0d:ea:6d:
//     b1:66:64:7a:71:91:13:63:86:fe:ca:94:d4:47:51:
//     39:66:ff:43:d5:62:de:f2:f2:41:3c:2e:3f:95:18:
//     2d:23:f7:e7:8e:75:19:3b:c6:50:fb:d9:90:f5:e8:
//     12:b7:b8:6a:43
// ASN1 OID: prime256v1
// NIST CURVE: P-256
// writing EC key
// -----BEGIN PUBLIC KEY-----
// MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEXRpP2b1JnuT9VSwN6m2xZmR6cZET
// Y4b+ypTUR1E5Zv9D1WLe8vJBPC4/lRgtI/fnjnUZO8ZQ+9mQ9egSt7hqQw==
// -----END PUBLIC KEY-----

// The public key is shown in two different formats.
// The first is this:

// pub:
//     04:5d:1a:4f:d9:bd:49:9e:e4:fd:55:2c:0d:ea:6d:
//     b1:66:64:7a:71:91:13:63:86:fe:ca:94:d4:47:51:
//     39:66:ff:43:d5:62:de:f2:f2:41:3c:2e:3f:95:18:
//     2d:23:f7:e7:8e:75:19:3b:c6:50:fb:d9:90:f5:e8:
//     12:b7:b8:6a:43

// It is the ANSI X9.63 format.
// 65-bytes are the uncompressed public key (04 || X || Y) 

// This is the same public key, but in PEM format

// -----BEGIN PUBLIC KEY-----
// MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEXRpP2b1JnuT9VSwN6m2xZmR6cZET
// Y4b+ypTUR1E5Zv9D1WLe8vJBPC4/lRgtI/fnjnUZO8ZQ+9mQ9egSt7hqQw==
// -----END PUBLIC KEY-----

// It contains ASN.1 that more explicitly identifies the key type.
// 
// SEQUENCE (2 elem)
//   SEQUENCE (2 elem)
//     OBJECT IDENTIFIER 1.2.840.10045.2.1 ecPublicKey (ANSI X9.62 public key type)
//     OBJECT IDENTIFIER 1.2.840.10045.3.1.7 prime256v1 (ANSI X9.62 named elliptic curve)
//   BIT STRING (520 bit) 000001000101110100011010010011111101100110111101010010011001111011100...

// PEM format can be loaded into a Chilkat public key object like this:

loo_SbPem = create oleobject
li_rc = loo_SbPem.ConnectToNewObject("Chilkat.StringBuilder")
if li_rc < 0 then
    destroy loo_SbPem
    MessageBox("Error","Connecting to COM object failed")
    return
end if
loo_SbPem.Append("-----BEGIN PUBLIC KEY-----~r~n")
loo_SbPem.Append("MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEXRpP2b1JnuT9VSwN6m2xZmR6cZET~r~n")
loo_SbPem.Append("Y4b+ypTUR1E5Zv9D1WLe8vJBPC4/lRgtI/fnjnUZO8ZQ+9mQ9egSt7hqQw==~r~n")
loo_SbPem.Append("-----END PUBLIC KEY-----~r~n")

loo_PubKey1 = create oleobject
li_rc = loo_PubKey1.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey1.LoadFromString(loo_SbPem.GetAsString())
if li_Success = 0 then
    Write-Debug loo_PubKey1.LastErrorText
    destroy loo_SbPem
    destroy loo_PubKey1
    return
end if

// The X9.63 format can be loaded like this:
loo_SbHex = create oleobject
li_rc = loo_SbHex.ConnectToNewObject("Chilkat.StringBuilder")

loo_SbHex.Append("04:5d:1a:4f:d9:bd:49:9e:e4:fd:55:2c:0d:ea:6d:")
loo_SbHex.Append("b1:66:64:7a:71:91:13:63:86:fe:ca:94:d4:47:51:")
loo_SbHex.Append("39:66:ff:43:d5:62:de:f2:f2:41:3c:2e:3f:95:18:")
loo_SbHex.Append("2d:23:f7:e7:8e:75:19:3b:c6:50:fb:d9:90:f5:e8:")
loo_SbHex.Append("12:b7:b8:6a:43")

// Get rid of the ":" chars.
li_NumReplaced = loo_SbHex.Replace(":","")

// We'll need to convert hex to base64..
loo_BdKey = create oleobject
li_rc = loo_BdKey.ConnectToNewObject("Chilkat.BinData")

loo_BdKey.AppendEncoded(loo_SbHex.GetAsString(),"hex")

loo_PubKey2 = create oleobject
li_rc = loo_PubKey2.ConnectToNewObject("Chilkat.PublicKey")

li_Success = loo_PubKey2.LoadFromString(loo_BdKey.GetEncoded("base64"))
if li_Success = 0 then
    Write-Debug loo_PubKey2.LastErrorText
    destroy loo_SbPem
    destroy loo_PubKey1
    destroy loo_SbHex
    destroy loo_BdKey
    destroy loo_PubKey2
    return
end if

// Let's get the key in pubKey2 as PEM.
// It should be idential to the PEM above.
Write-Debug loo_PubKey2.GetPem(1)

// Here's the output.  You can see it's the same as the PEM above..

// -----BEGIN PUBLIC KEY-----
// MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEXRpP2b1JnuT9VSwN6m2xZmR6cZET
// Y4b+ypTUR1E5Zv9D1WLe8vJBPC4/lRgtI/fnjnUZO8ZQ+9mQ9egSt7hqQw==
// -----END PUBLIC KEY-----


destroy loo_SbPem
destroy loo_PubKey1
destroy loo_SbHex
destroy loo_BdKey
destroy loo_PubKey2