(Visual Basic 6.0) JWE Using General JWE JSON Serialization

This example duplicates the example A.4 in RFC 7516 for JSON Web Encryption (JWE).

This example demonstrates the capability for encrypting the same plaintext to multiple recipients. Two recipients are present in this example.

Note: This example requires Chilkat v9.5.0.66 or greater.

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' This requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' Note: This example requires Chilkat v9.5.0.66 or greater.

Dim success As Long
Dim plaintext As String
plaintext = "Live long and prosper."

Dim jwe As New ChilkatJwe

' First build the JWE Protected Header: {"enc":"A128CBC-HS256"}
Dim jweProtHdr As New ChilkatJsonObject
success = jweProtHdr.AppendString("enc","A128CBC-HS256")
success = jwe.SetProtectedHeader(jweProtHdr)

' The first recipient uses the RSAES-PKCS1-v1_5 algorithm to encrypt
' the CEK.  The second uses AES Key Wrap to encrypt the CEK.  Key ID
' values are supplied for both keys.  The two JWE Per-Recipient
' Unprotected Header values used to represent these algorithms and key
' IDs are:
' 
'      {"alg":"RSA1_5","kid":"2011-04-29"}
' 
' and
' 
'      {"alg":"A128KW","kid":"7"}

Dim jweRecipientHdr1 As New ChilkatJsonObject
success = jweRecipientHdr1.AppendString("alg","RSA1_5")
success = jweRecipientHdr1.AppendString("kid","2011-04-29")
Dim recipientIndex As Long
recipientIndex = 0
success = jwe.SetRecipientHeader(recipientIndex,jweRecipientHdr1)

Dim jweRecipientHdr2 As New ChilkatJsonObject
success = jweRecipientHdr2.AppendString("alg","A128KW")
success = jweRecipientHdr2.AppendString("kid","7")
recipientIndex = 1
success = jwe.SetRecipientHeader(recipientIndex,jweRecipientHdr2)

' Set the Shared Unprotected Header:  {"jku":"https://server.example.com/keys.jwks"}
Dim jweUnprotHdr As New ChilkatJsonObject
success = jweUnprotHdr.AppendString("jku","https://server.example.com/keys.jwks")
success = jwe.SetUnprotectedHeader(jweUnprotHdr)

' Note: The intent of specifying a "kid" (an acronym for "Key ID") is that
' the software would somehow download the keys.jwks from https://server.example.com/keys.jwks,
' and would select the key (whatever format it may be, such as RSA, or an AES key wrap key, etc.),
' and then automatically use it. 

' This example keeps the "kid" and "jku" in their respective headers, but does not actually fetch
' the keys from some URL.  We'll just provide the keys directly..

' Recipient 0 uses this RSA key:
Dim sbJwk As New ChilkatStringBuilder
success = sbJwk.Append("{""kty"":""RSA"",")
success = sbJwk.Append("""n"":""sXchDaQebHnPiGvyDOAT4saGEUetSyo9MKLOoWFsueri23bOdgWp4Dy1Wl")
success = sbJwk.Append("UzewbgBHod5pcM9H95GQRV3JDXboIRROSBigeC5yjU1hGzHHyXss8UDpre")
success = sbJwk.Append("cbAYxknTcQkhslANGRUZmdTOQ5qTRsLAt6BTYuyvVRdhS8exSZEy_c4gs_")
success = sbJwk.Append("7svlJJQ4H9_NxsiIoLwAEk7-Q3UXERGYw_75IDrGA84-lA_-Ct4eTlXHBI")
success = sbJwk.Append("Y2EaV7t7LjJaynVJCpkv4LKjTTAumiGUIuQhrNhZLuF_RJLqHpM2kgWFLU")
success = sbJwk.Append("7-VTdL1VbC2tejvcI2BlMkEpk1BzBZI0KQB0GaDWFLN-aEAw3vRw"",")
success = sbJwk.Append("""e"":""AQAB"",")
success = sbJwk.Append("""d"":""VFCWOqXr8nvZNyaaJLXdnNPXZKRaWCjkU5Q2egQQpTBMwhprMzWzpR8Sxq")
success = sbJwk.Append("1OPThh_J6MUD8Z35wky9b8eEO0pwNS8xlh1lOFRRBoNqDIKVOku0aZb-ry")
success = sbJwk.Append("nq8cxjDTLZQ6Fz7jSjR1Klop-YKaUHc9GsEofQqYruPhzSA-QgajZGPbE_")
success = sbJwk.Append("0ZaVDJHfyd7UUBUKunFMScbflYAAOYJqVIVwaYR5zWEEceUjNnTNo_CVSj")
success = sbJwk.Append("-VvXLO5VZfCUAVLgW4dpf1SrtZjSt34YLsRarSb127reG_DUwg9Ch-Kyvj")
success = sbJwk.Append("T1SkHgUWRVGcyly7uvVGRSDwsXypdrNinPA4jlhoNdizK2zF2CWQ"",")
success = sbJwk.Append("""p"":""9gY2w6I6S6L0juEKsbeDAwpd9WMfgqFoeA9vEyEUuk4kLwBKcoe1x4HG68")
success = sbJwk.Append("ik918hdDSE9vDQSccA3xXHOAFOPJ8R9EeIAbTi1VwBYnbTp87X-xcPWlEP")
success = sbJwk.Append("krdoUKW60tgs1aNd_Nnc9LEVVPMS390zbFxt8TN_biaBgelNgbC95sM"",")
success = sbJwk.Append("""q"":""uKlCKvKv_ZJMVcdIs5vVSU_6cPtYI1ljWytExV_skstvRSNi9r66jdd9-y")
success = sbJwk.Append("BhVfuG4shsp2j7rGnIio901RBeHo6TPKWVVykPu1iYhQXw1jIABfw-MVsN")
success = sbJwk.Append("-3bQ76WLdt2SDxsHs7q7zPyUyHXmps7ycZ5c72wGkUwNOjYelmkiNS0"",")
success = sbJwk.Append("""dp"":""w0kZbV63cVRvVX6yk3C8cMxo2qCM4Y8nsq1lmMSYhG4EcL6FWbX5h9yuv")
success = sbJwk.Append("ngs4iLEFk6eALoUS4vIWEwcL4txw9LsWH_zKI-hwoReoP77cOdSL4AVcra")
success = sbJwk.Append("Hawlkpyd2TWjE5evgbhWtOxnZee3cXJBkAi64Ik6jZxbvk-RR3pEhnCs"",")
success = sbJwk.Append("""dq"":""o_8V14SezckO6CNLKs_btPdFiO9_kC1DsuUTd2LAfIIVeMZ7jn1Gus_Ff")
success = sbJwk.Append("7B7IVx3p5KuBGOVF8L-qifLb6nQnLysgHDh132NDioZkhH7mI7hPG-PYE_")
success = sbJwk.Append("odApKdnqECHWw0J-F0JWnUd6D2B_1TvF9mXA2Qx-iGYn8OVV1Bsmp6qU"",")
success = sbJwk.Append("""qi"":""eNho5yRBEBxhGBtQRww9QirZsB66TrfFReG_CcteI1aCneT0ELGhYlRlC")
success = sbJwk.Append("tUkTRclIfuEPmNsNDPbLoLqqCVznFbvdB7x-Tl-m0l_eFTj2KiqwGqE9PZ")
success = sbJwk.Append("B9nNTwMVvH3VRRSLWACvPnSiwP8N5Usy-WRXS-V7TbpxIhvepTfE0NNo""")
success = sbJwk.Append("}")

' Load this JWK into a Chilkat private key object.
Dim rsaPrivKey As New PrivateKey
success = rsaPrivKey.LoadJwk(sbJwk.GetAsString())
If (success <> 1) Then
    Debug.Print rsaPrivKey.LastErrorText
    Exit Sub
End If

' Get the public key for encryption.  (The RSA private key is used for decryption.)
Dim rsaPubKey As PublicKey
Set rsaPubKey = rsaPrivKey.GetPublicKey()
recipientIndex = 0
success = jwe.SetPublicKey(recipientIndex,rsaPubKey)

' Recipient 1 uses AES Key Wrap
Dim aesWrappingKey As String
aesWrappingKey = "GawgguFyGrWKav7AX4VKUg"
recipientIndex = 1
success = jwe.SetWrappingKey(recipientIndex,aesWrappingKey,"base64url")

' OK.. everything has been specified.
' Now encrypt.  Chilkat will use the general JSON serialization because it is only
' possible serializationto use given there are multiple recipients. 
Dim strJwe As String
strJwe = jwe.Encrypt(plaintext,"utf-8")
If (jwe.LastMethodSuccess <> 1) Then
    Debug.Print jwe.LastErrorText
    Exit Sub
End If

' The strJwe is in the most compact form possible (a single line).
' Let's load it into a JSON object and examine in a non-compact pretty-printed format:
Dim jsonTemp As New ChilkatJsonObject
success = jsonTemp.Load(strJwe)
jsonTemp.EmitCompact = 0
Debug.Print jsonTemp.Emit()

' The JWE looks like this:
' (Note: Because of random values used in the encryption process, your encrypted results will be different.)

' 	{ 
' 	  "protected": "eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0",
' 	  "unprotected": { 
' 	    "jku": "https://server.example.com/keys.jwks"
' 	  },
' 	  "recipients": [
' 	    { 
' 	      "header": { 
' 	        "alg": "RSA1_5",
' 	        "kid": "2011-04-29"
' 	      },
' 	      "encrypted_key": "WlUggejR-vStJVNKgjG2mQrVv74aga1FFutT8E-n-yJEOTsOVnGjhj1NW_Snd9DqHAhFrc7NEvKCFplKWGnusBZxxjm1JpdUa0MIpkGmncJHQQdfm21vcbEUbDmfqVY79SnEis3tih1D3qmyp_Bxti4byDAHJIOJv_cj0Sx8oHZzgGtOLjtHsydyo1MtBIqI0w86i_uhUuraihZ3ngj67YZ6uqpR6lulkPIVohfF3oJ0D3Ay_XOCHWlHYkTg6VZsa0FDrPtfB2pG3TxTBPwI4IMj5uF_D3zrg51dCYKU1Gah71ujLaXRE5q9XF7oOknxiWQuWc7Ox8JP03lSx-DiVA"
' 	    },
' 	    { 
' 	      "header": { 
' 	        "alg": "A128KW",
' 	        "kid": "7"
' 	      },
' 	      "encrypted_key": "8diBP2aUUB_Jl5WxCuMJLN6HsppE3rhSjcecee0fBcwB31zbPAVejQ"
' 	    } 
' 	  ],
' 	  "iv": "JqahFKx5Z8SFT_LnkfOq0Q",
' 	  "ciphertext": "YcSdjlszsaY1ADcs4Vw85H_WoAqnkDIJaJsTkmCj05s",
' 	  "tag": "G3KF2CZ-DMhm0cqUbhJKMA"
' 	} 

' To decrypt, we don't need both recipient keys.  We can decrypt with one key or the other.
' The FindRecipient method can be used to find a particular recipient index.

' First, load the JWE..
Dim jwe2 As New ChilkatJwe
success = jwe2.LoadJwe(strJwe)
If (success <> 1) Then
    Debug.Print jwe2.LastErrorText
    Exit Sub
End If

' Let's say we have the AES key wrap key, and we know the "kid" equals "7".
Dim caseSensitive As Long
caseSensitive = 0
recipientIndex = jwe2.FindRecipient("kid","7",caseSensitive)
If (recipientIndex < 0) Then
    Debug.Print "Unable to find recipient with kid=7"
    Exit Sub
End If

' Set the AES wrap key for the recipient index.
success = jwe2.SetWrappingKey(recipientIndex,aesWrappingKey,"base64url")

' Decrypt
Dim originalPlaintext As String
originalPlaintext = jwe2.Decrypt(recipientIndex,"utf-8")
If (jwe2.LastMethodSuccess <> 1) Then
    Debug.Print jwe2.LastErrorText
    Exit Sub
End If

Debug.Print "original text decrypted with AES key wrap key: "
Debug.Print originalPlaintext

' Now, let's do the same with the RSA private key:
recipientIndex = jwe2.FindRecipient("kid","2011-04-29",caseSensitive)
If (recipientIndex < 0) Then
    Debug.Print "Unable to find recipient with kid=2011-04-29"
    Exit Sub
End If

' Set the RSA private key for the recipient index.
success = jwe2.SetPrivateKey(recipientIndex,rsaPrivKey)

' Decrypt
originalPlaintext = jwe2.Decrypt(recipientIndex,"utf-8")
If (jwe2.LastMethodSuccess <> 1) Then
    Debug.Print jwe2.LastErrorText
    Exit Sub
End If

Debug.Print "original text decrypted with RSA private key: "
Debug.Print originalPlaintext

' ---------------------------------------------------------------------------------
' It should also be possible to decrypt the JWE as shown in RFC 7516, Appendix A.4.7
' because it was produced using the same keys.

Dim sbJwe As New ChilkatStringBuilder
success = sbJwe.Append("{")
success = sbJwe.Append("""protected"":")
success = sbJwe.Append("""eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0"",")
success = sbJwe.Append("""unprotected"":")
success = sbJwe.Append("{""jku"":""https://server.example.com/keys.jwks""},")
success = sbJwe.Append("""recipients"":[")
success = sbJwe.Append("{""header"":")
success = sbJwe.Append("{""alg"":""RSA1_5"",""kid"":""2011-04-29""},")
success = sbJwe.Append("""encrypted_key"":")
success = sbJwe.Append("""UGhIOguC7IuEvf_NPVaXsGMoLOmwvc1GyqlIKOK1nN94nHPoltGRhWhw7Zx0-")
success = sbJwe.Append("kFm1NJn8LE9XShH59_i8J0PH5ZZyNfGy2xGdULU7sHNF6Gp2vPLgNZ__deLKx")
success = sbJwe.Append("GHZ7PcHALUzoOegEI-8E66jX2E4zyJKx-YxzZIItRzC5hlRirb6Y5Cl_p-ko3")
success = sbJwe.Append("YvkkysZIFNPccxRU7qve1WYPxqbb2Yw8kZqa2rMWI5ng8OtvzlV7elprCbuPh")
success = sbJwe.Append("cCdZ6XDP0_F8rkXds2vE4X-ncOIM8hAYHHi29NX0mcKiRaD0-D-ljQTP-cFPg")
success = sbJwe.Append("wCp6X-nZZd9OHBv-B3oWh2TbqmScqXMR4gp_A""},")
success = sbJwe.Append("{""header"":")
success = sbJwe.Append("{""alg"":""A128KW"",""kid"":""7""},")
success = sbJwe.Append("""encrypted_key"":")
success = sbJwe.Append("""6KB707dM9YTIgHtLvtgWQ8mKwboJW3of9locizkDTHzBC2IlrT1oOQ""}],")
success = sbJwe.Append("""iv"":")
success = sbJwe.Append("""AxY8DCtDaGlsbGljb3RoZQ"",")
success = sbJwe.Append("""ciphertext"":")
success = sbJwe.Append("""KDlTtXchhZTGufMYmOYGS4HffxPSUrfmqCHXaI9wOGY"",")
success = sbJwe.Append("""tag"":")
success = sbJwe.Append("""Mz-VPPyU4RlcuYv1IwIvzw""")
success = sbJwe.Append("}")

success = jwe2.LoadJweSb(sbJwe)
If (success <> 1) Then
    Debug.Print jwe2.LastErrorText
    Exit Sub
End If

' We can decrypt with either key.  Let's use the AES key wrap key...
recipientIndex = jwe2.FindRecipient("kid","7",caseSensitive)
If (recipientIndex < 0) Then
    Debug.Print "Unable to find recipient with kid=7"
    Exit Sub
End If

' Set the AES wrap key for the recipient index.
success = jwe2.SetWrappingKey(recipientIndex,aesWrappingKey,"base64url")

' Decrypt
originalPlaintext = jwe2.Decrypt(recipientIndex,"utf-8")
If (jwe2.LastMethodSuccess <> 1) Then
    Debug.Print jwe2.LastErrorText
    Exit Sub
End If

Debug.Print "original text decrypted from published JWE, with AES key wrap key: "
Debug.Print originalPlaintext

' The output:

' original text decrypted with AES key wrap key: 
' Live long and prosper.
' original text decrypted with RSA private key: 
' Live long and prosper.
' original text decrypted from published JWE, with AES key wrap key: 
' Live long and prosper.