diff --git a/docs/content/s3.md b/docs/content/s3.md
index a71549e94..f3fcce916 100644
--- a/docs/content/s3.md
+++ b/docs/content/s3.md
@@ -1271,13 +1271,13 @@ Properties:
 
 #### --s3-sse-customer-algorithm
 
-If using SSE-C, the server-side encryption algorithm used when storing this object in S3.
+If using SSE-C, the server-side encryption algorithm used when storing this object in S3.  As per AWS S3 standard, this must be "AES256" if SSE-C is used.
 
 Properties:
 
 - Config:      sse_customer_algorithm
 - Env Var:     RCLONE_S3_SSE_CUSTOMER_ALGORITHM
-- Provider:    AWS,Ceph,ChinaMobile,Minio
+- Provider:    AWS,Ceph,ChinaMobile,Minio, IDrive (if enabled via dashboard)
 - Type:        string
 - Required:    false
 - Examples:
@@ -1288,15 +1288,13 @@ Properties:
 
 #### --s3-sse-customer-key
 
-To use SSE-C you may provide the secret encryption key used to encrypt/decrypt your data.
-
-Alternatively you can provide --sse-customer-key-base64.
+To use SSE-C you must provide a 32 byte secret encryption key to encrypt/decrypt your data either using this option or --sse-customer-key-base64.
 
 Properties:
 
 - Config:      sse_customer_key
 - Env Var:     RCLONE_S3_SSE_CUSTOMER_KEY
-- Provider:    AWS,Ceph,ChinaMobile,Minio
+- Provider:    AWS,Ceph,ChinaMobile,Minio, IDrive (if enabled via dashboard)
 - Type:        string
 - Required:    false
 - Examples:
@@ -1305,9 +1303,7 @@ Properties:
 
 #### --s3-sse-customer-key-base64
 
-If using SSE-C you must provide the secret encryption key encoded in base64 format to encrypt/decrypt your data.
-
-Alternatively you can provide --sse-customer-key.
+If using SSE-C you must provide the 32 byte secret encryption key encoded in base64 format to encrypt/decrypt your data.  Alternatively you can provide --sse-customer-key.
 
 Properties: