I have to process SMIME messages that are signed and encrypted.
Loading a SMIME message and use "mime.Decrypt2( myCert, myPk )" seems to work fine.
But, I wanted to check that a modified message will not succeed so I decrypted the message using another tool.
I then loaded the decrypted message into a new mime object and used "mime.UnwrapSecurity()".
It returns true, but the logs shows lots of lines with:
unwrap multipart/signed: number of parts is not equal to 2
If I then modify the decrypted message and run it through the same verification, I would expect it to fail on "mime.UnwrapSecurity()" but it still returns true! The log messages are identical.
I also tried using "mime.Verify()" but I get the same result, with similar logs.
What do I need to do to be sure that UnwrapSecurity()/Verify() will fail if the message has been altered?
My code is in C# and like this:
var mime = new Chilkat.Mime();
mime.VerboseLogging = true;
mime.LoadMimeFile( "decrypted.txt" );
bool isSigned = mime.ContainsSignedParts(); // returns true
bool ok = mime.UnwrapSecurity(); // of Verify(), both returns true
Console.WriteLine( "Log: " + mime.LastErrorText );
Logs (removed lots of duplicate lines where indicated):
IsUnlocked:
ChilkatVersion: 9.5.0.72
Product is not unlocked. Make sure to call UnlockComponent first.
(leaveContext 16ms)
UnlockComponent:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: NONE
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
component: Mime
unlockCode: Start my 30-day Trial
regKeyUnlock:
product: ChilkatSMIME
hcCurDate: Mon, 12 Mar 2018 14:57:05 +0100
hcExpire: 5/2018
Component successfully unlocked using trial key
(leaveContext 15ms)
Success.
(leaveContext 15ms)
IsUnlocked:
ChilkatVersion: 9.5.0.72
(leaveContext)
LoadMimeFile:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
path: D:\decrypted.txt
loadFileX:
(leaveContext)
numMimeBytes: 56202
loadMimeBinary:
loadMimeComplete:
findEndOfHeader2:
(leaveContext)
loadMimeHeaderText:
(leaveContext)
parseMimeBody:
(leaveContext)
(leaveContext)
(leaveContext)
Success.
(leaveContext 31ms)
NumParts:
ChilkatVersion: 9.5.0.72
NumParts: 0
(leaveContext)
ContainsEncryptedParts:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
(leaveContext)
ContainsEncryptedParts:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
(leaveContext 16ms)
ContainsEncryptedParts:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
(leaveContext)
UnwrapSecurity:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
unwrapInner2:
Unwrapping multipart/signed...
unwrapMultipartSigned:
unwrap multipart/signed: number of parts is not equal to 2
num_parts: 0
(leaveContext)
Unwrapping multipart/signed...
unwrapMultipartSigned:
unwrap multipart/signed: number of parts is not equal to 2
num_parts: 0
(leaveContext)
... cut out identical messages ...
unwrapMultipartSigned:
unwrap multipart/signed: number of parts is not equal to 2
num_parts: 0
(leaveContext)
(leaveContext 31ms)
This message was signed, but not encrypted
All signatures are valid
num_parts_signed: 30
Success.
(leaveContext 31ms)
Verify:
DllDate: Feb 12 2018
ChilkatVersion: 9.5.0.72
UnlockPrefix: Start my 30-day Trial
Architecture: Little Endian; 32-bit
Language: .NET 4.6 VS2017
VerboseLogging: 1
unwrapSignedNoRecursion:
contentType: multipart/signed
multipart signed...
unwrapMultipartSigned:
unwrap multipart/signed: number of parts is not equal to 2
num_parts: 0
(leaveContext)
(leaveContext)
(leaveContext 16ms)
