Use the word "complement" instead of "alternative"

Closes #16

1 files changed, 12 insertions, 6 deletions

diff --git a/sq-guide.md b/sq-guide.md
index 05d8abe..f448b8f 100644
--- a/sq-guide.md
+++ b/sq-guide.md
@@ -307,12 +307,13 @@ for links to explanations.
 
 ## Symmetric cryptography
 
-The alternative to public key cryptography is _symmetric
-cryptography_. (Public key cryptography is also known as _asymmetric
-cryptography_.) In symmetric cryptography there is no public and
-private parts of an encryption key. There is only one part, and the
-same key is used both for encrypting and for decrypting data. This is
-in many ways easier to understand, but is usually more awkward to use.
+The complement to public key cryptography is _secret key
+cryptography_, which is also known as _symmetric cryptography_.
+(Public key cryptography is also known as _asymmetric cryptography_.)
+In symmetric cryptography there is no public and private parts of an
+encryption key. There is only one part, and the same key is used both
+for encrypting and for decrypting data. This is in many ways easier to
+understand, but is usually more awkward to use.
 
 Symmetric cryptography is best suited when only one person needs to
 know the key, or when everyone who needs the key can get it in person.
@@ -345,6 +346,11 @@ The benefit is that symmetric cryptography tends to run faster and
 have shorter keys compared to public key cryptography, for similar
 levels of resistance against attacks.
 
+OpenPGP actually uses both symmetric and public key cryptography: one
+for the bulk of encryption, for speed, and the other for easier key
+management. The user does not actually need to care, but understanding
+is always good.
+
 
 ## Limitations of cryptography