Can I decrypt TDE transaction log files for use with 3rd party software? Is there a way to decrypt TDE log files on disk for use with 3rd party software? I have the original key and certificates. I am trying to use the transaction files with a 3rd party tool in order to recover some lost data.
Is there a way to decrypt TDE log files on disk for use with 3rd party software?
The short answer is -- this cannot be done.

Encryption of the database file is performed at the page level. The pages in an encrypted database are encrypted before they are written to disk and decrypted when read into memory. TDE does not increase the size of the encrypted database.
[...] When the data is written from buffer pool to disk (MDF, LDF &amp; NDF) the data is first encrypted and then then encrypted data will be sent to disk.
When the data is read from  the disk, first the data will be decrypted and then it will be sent to buffer pool.

Taken from How to enable/remove Transparent Data Encryption (TDE).
See also SQL Server 2008 Transparent Data Encryption.