SPIEGEL: You worked with the Hauptverwaltung Aufklärung (HVA), East Germany's foreign intelligence agency within the Ministry for State Security, or Stasi. From the perspective of a professional, how good was the NSA in the 1980s?
Eichner: Among all the Western agencies that were involved in communications intelligence, the NSA was the leader and the top intelligence agency -- from the perspective of both their equipment and their personnel.
SPIEGEL: How eager was the NSA back then to collect data?
Eichner: Even then, they wanted to know everything, but they didn't have all of the technical abilities to collect and process it all.
SPIEGEL: In your book about the NSA, which was just recently published, you describe how the Stasi managed to access internal NSA information.